Co-ordinate Geometry

ICSE Class 9 Mathematics · Selina Solutions Concise Mathematics Class 9 ICSE · 97 solved questions

Exercise
1(a)Exercise 23(A)

In equation 2x - 5 = 0; ordinate is :

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In the equation 2x − 5 = 0, we need to find the ordinate, which means the y-coordinate of a point on the graph of this equation.

2x - 5 = 0

⇒ 2x = 5

⇒ x = $\frac{5}{2}$

⇒ x = 2.5

Notice that this equation only involves x and has no y-term. This tells us that the equation represents a vertical line parallel to y-axis at x = 2.5. Hence, ordinate = 0 (i.e., y = 0).

Hence, option 1 is the correct option.

1(b)Exercise 23(A)

In equation $y = 3 + \frac{4x}{5}$, the independent variable is :

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Given:

$y = 3 + \frac{4x}{5}$

In the above equation, the value of y depends on the value of x, so y is said to be dependent variable and x is said to be independent variable.

Hence, option 2 is the correct option.

1(c)Exercise 23(A)

If (2x - 1, y + 5) = (3, 10), the values of x and y are :

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Since two ordered pairs are equal, their first components are equal and their second components are separately equal.

(2x - 1, y + 5) = (3, 10)

⇒ 2x - 1 = 3 and y + 5 = 10

⇒ 2x = 3 + 1 and y = 10 - 5

⇒ 2x = 4 and y = 5

⇒ x = $\frac{4}{2}$ and y = 5

⇒ x = 2 and y = 5

Hence, option 3 is the correct option.

1(d)Exercise 23(A)

(5, -7) belongs to :

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(5, -7) belongs to : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The point (5, -7) has a positive x-coordinate and a negative y-coordinate. This places it in the 4th quadrant.

Hence, option 4 is the correct option.

1(e)Exercise 23(A)

Abscissa of a point is the solution of equation 3x - 2 = 7 and its ordinate is the solution of equation 8 - 3y = 2. The point is :

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Given:

3x - 2 = 7

⇒ 3x = 7 + 2

⇒ 3x = 9

⇒ x = $\frac{9}{3}$

⇒ x = 3

And, 8 - 3y = 2

⇒ 3y = 8 - 2

⇒ 3y = 6

⇒ y = $\frac{6}{3}$

⇒ y = 2

Therefore, the co-ordinates of the point = (3, 2).

Hence, option 1 is the correct option.

2Exercise 23(A)

For each equation given below; name the dependent and independent variables.

(i) $y = \frac{4}{3}x - 7$

(ii) x = 9y + 4

(iii) $x = \frac{5y + 3}{2}$

(iv) $y = \frac{1}{7}(6x + 5)$

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(i) $y = \frac{4}{3}x - 7$

In the above equation, the value of y depends on the value of x, so y is said to be dependent variable and x is said to be independent variable.

Hence, x = independent variable and y = dependent variable.

(ii) x = 9y + 4

In the above equation, the value of x depends on the value of y, so x is said to be dependent variable and y is said to be independent variable.

Hence, x = dependent and y = independent.

(iii) $x = \frac{5y + 3}{2}$

In the above equation, the value of x depends on the value of y, so x is said to be dependent variable and y is said to be independent variable.

Hence, x = dependent and y = independent.

(iv) $y = \frac{1}{7}(6x + 5)$

In the above equation, the value of y depends on the value of x, so y is said to be dependent variable and x is said to be independent variable.

Hence, x = independent and y = dependent.

3Exercise 23(A)

Plot the following points on the same graph paper :

(i) (8, 7)

(ii) (3, 6)

(iii) (0, 4)

(iv) (0, -4)

(v) (3, -2)

(vi) (-2, 5)

(vii) (-3, 0)

(viii) (5, 0)

(ix) (-4, -3)

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Plot the following points on the same graph paper : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4Exercise 23(A)

Find the values of x and y if :

(i) (x - 1, y + 3) = (4, 4)

(ii) (3x + 1, 2y - 7) = (9, - 9)

(iii) (5x - 3y, y - 3x) = (4, - 4)

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Since two ordered pairs are equal, their first components are equal and their second components are separately equal.

(i) (x - 1, y + 3) = (4, 4)

⇒ x - 1 = 4 and y + 3 = 4

⇒ x = 4 + 1 and y = 4 - 3

⇒ x = 5 and y = 1

Hence, x = 5 and y = 1.

(ii) (3x + 1, 2y - 7) = (9, - 9)

⇒ 3x + 1 = 9 and 2y - 7 = -9

⇒ 3x = 9 - 1 and 2y = -9 + 7

⇒ 3x = 8 and 2y = -2

⇒ x = $\frac{8}{3}$ and y = -$\frac{2}{2}$

⇒ x = $2\frac{2}{3}$ and y = -1

Hence, x = $2\frac{2}{3}$ and y = -1.

(iii) (5x - 3y, y - 3x) = (4, - 4)

⇒ 5x - 3y = 4 ................(1)

And, y - 3x = - 4

⇒ y = -4 + 3x ................(2)

Putting the value of y in (1), we get

⇒ 5x - 3(-4 + 3x) = 4

⇒ 5x + 12 - 9x = 4

⇒ 5x - 9x = 4 - 12

⇒ - 4x = - 8

⇒ x = $\frac{8}{4}$

⇒ x = 2

Putting the value of x in (2),

y = - 4 + 3x

⇒ y = - 4 + 3 x 2

⇒ y = - 4 + 6

⇒ y = 2

Hence, x = 2 and y = 2.

5Exercise 23(A)

Use the graph given below, to find the co-ordinates of the point (s) satisfying the given conditions :

(i) the abscissa is 2.

(ii) the ordinate is 0.

(iii) the ordinate is 3.

(iv) the ordinate is - 4.

(v) the abscissa is 5.

(vi) the abscissa is equal to the ordinate.

(vii) the ordinate is half of the abscissa.

Use the graph given below, to find the co-ordinates of the point (s) satisfying the given conditions : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
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(i) The abscissa is 2.

The abscissa represents the x-coordinate, so x = 2.

Observing the graph, the y-coordinate for this point is also 2.

Hence, the point is A = (2, 2).

(ii) The ordinate is 0.

The ordinate represents the y-coordinate, so y = 0.

Observing the graph, the x-coordinate for this point is 5.

Hence, the point is B = (5, 0).

(iii) The ordinate is 3.

The ordinate represents the y-coordinate, so y = 3.

Observing the graph, the x-coordinates for this point are -4 and 6.

Hence, the points are C = (-4, 3) and E = (6, 3).

(iv) The ordinate is - 4.

The ordinate represents the y-coordinate, so y = - 4.

Observing the graph, the x-coordinate for this point is 2.

Hence, the point is D = (2, -4).

(v) The abscissa is 5.

The abscissa represents the x-coordinate, so x = 5.

Observing the graph, the y-coordinates for this point are 0, 5 and -3.

Hence, the points are B = (5, 0), H = (5, 5) and G = (5, -3).

(vi) The abscissa is equal to the ordinate.

The abscissa represents the x-coordinate, and ordinate represents the y-coordinate so x = y.

Observing the graph, the points are (2,2), (5, 5) and (4, 4).

Hence, the points are A = (2, 2), H = (5, 5) and I = (4, 4).

(vii) The ordinate is half of the abscissa.

The abscissa represents the x-coordinate, and ordinate represents the y-coordinate so y = $\frac{\text{x}}{2}$.

Observing the graph, the point is (6, 3).

Hence, the point is E = (6, 3).

6Exercise 23(A)

State, true or false :

(i) The ordinate of a point is its x-co-ordinate.

(ii) The origin is in the first quadrant.

(iii) The y-axis is the vertical number line.

(iv) Every point is located in one of the four quadrants.

(v) If the ordinate of a point is equal to its abscissa; the point lies either in the first quadrant or in the second quadrant.

(vi) The origin (0, 0) lies on the x-axis.

(vii) The point (a, b) lies on the y-axis if b = 0.

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(i) False

Reason :

The ordinate is the y-co-ordinate of a point.

(ii) False

Reason :

The origin (0, 0) is the point where the x-axis and y-axis intersect.

(iii) True

Reason :

The y-axis is the vertical number line and the x-axis is the horizontal number line in the coordinate plane.

(iv) False

Reason :

Points that lie on the x-axis or y-axis are not located in any of the four quadrants.

(v) False

Reason :

If the ordinate (y-coordinate) equals the abscissa (x-coordinate), (x = y), the point lies either in the first quadrant (x > 0, y > 0) or the third quadrant (x < 0, y < 0).

(vi) True

Reason :

The origin (0, 0) lies on both the x-axis and y-axis, as it is the intersection point of the two axes.

(vii) False

Reason :

The point (a, b) lies on the y-axis if the x-coordinate a = 0, not b = 0.

7Exercise 23(A)

In each of the following, find the co-ordinates of the point whose abscissa is the solution of the first equation and ordinate is the solution of the second equation :

(i) 3 - 2x = 7; 2y + 1 = 10 - $2 \frac{1}{2}y$.

(ii) $\frac{2a}{3} - 1 = \frac{a}{2}; \frac{15 - 4b}{7} = \frac{2b - 1}{3}$

(iii) $5x -(5 - x) = \frac{1}{2}(3 - x); 4 - 3y = \frac{4 + y}{3}$

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(i) 3 - 2x = 7

⇒ 2x = 3 - 7

⇒ 2x = - 4

⇒ x = - $\frac{4}{2}$

⇒ x = - 2

2y + 1 = 10 - $2 \frac{1}{2}y$

⇒ 2y + $\frac{5}{2}y$ = 10 - 1

⇒ $\frac{4 + 5}{2}y$ = 9

⇒ $\frac{9}{2}y$ = 9

⇒ y = $\frac{2 \times 9}{9}$

⇒ y = 2

Hence, the co-ordinates of the point = (-2, 2).

(ii)

$$\begin{aligned}\frac{2a}{3} - 1 = \frac{a}{2}\\[1em] ⇒ \frac{2a}{3} - \frac{a}{2} = 1\\[1em] ⇒ \frac{4a - 3a}{6} = 1\\[1em] ⇒ \frac{a}{6} = 1\\[1em] ⇒ a = 6\\[1em]\end{aligned}$$

$$\begin{aligned}\frac{15 - 4b}{7} = \frac{2b - 1}{3}\\[1em] ⇒ 3(15 - 4b) = 7(2b - 1)\\[1em] ⇒ 45 - 12b = 14b - 7\\[1em] ⇒ 45 + 7 = 14b + 12b\\[1em] ⇒ 52 = 26b\\[1em] ⇒ b = \frac{52}{26}\\[1em] ⇒ b = 2\\[1em]\end{aligned}$$

Hence, the co-ordinates of the point = (6, 2).

(iii)

$$\begin{aligned}5x -(5 - x) = \frac{1}{2}(3 - x)\\[1em] ⇒ 5x - 5 + x = \frac{1}{2}(3 - x) \\[1em] ⇒ 6x - 5 = \frac{1}{2}(3 - x) \\[1em] ⇒ 2(6x - 5) = 3 - x\\[1em] ⇒ 12x + x = 3 + 10 \\[1em] ⇒ 13x = 13 \\[1em] ⇒ x = \frac{13}{13}\\[1em] ⇒ x = 1 \\[1em]\end{aligned}$$

$$\begin{aligned}4 - 3y = \frac{4 + y}{3}\\[1em] ⇒ 3(4 - 3y) = 4 + y\\[1em] ⇒ 12 - 9y = 4 + y\\[1em] ⇒ 12 - 4 = 9y + y\\[1em] ⇒ 8 = 10y\\[1em] ⇒ y = \frac{8}{10}\\[1em] ⇒ y = \frac{4}{5}\\[1em]\end{aligned}$$

Hence, the co-ordinates of the point = $\Big(1, \frac{4}{5}\Big)$.

8Exercise 23(A)

In each of the following, the co-ordinates of the three vertices of a rectangle ABCD are given. By plotting the given points; find, in each case, the co-ordinates of the fourth vertex :

(i) A (2, 0), B (8, 0) and C (8, 4).

(ii) A (4, 2), B (-2, 2) and D (4, -2).

(iii) A (- 4, - 6), C (6, 0) and D (- 4, 0)

(iv) B (10, 4), C (0, 4) and D (0, - 2).

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(i) After plotting the given points A(2, 0), B(8, 0) and C(8, 4) on a graph paper, join A with B and B with C. From the graph, it is clear that the vertical distance between the points B(8, 0) and C(8, 4) is 4 units. Therefore, the vertical distance between points A(2, 0) and D must be 4 units.

Now, complete the rectangle ABCD and read the coordinates of point D. As shown on the graph, D = (2, 4).

In each of the following, the co-ordinates of the three vertices of a rectangle ABCD are given. By plotting the given points; find, in each case, the co-ordinates of the fourth vertex : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, D = (2, 4).

(ii) After plotting the given points A(4, 2), B(-2, 2) and D(4, -2) on a graph paper, join A with B and A with D.

From the graph it is clear that the vertical distance between the points A(4, 2) and D(4, -2) is 4 units and the horizontal distance between the points A(4, 2) and B(-2, 2) is 6 units. Therefore, the vertical distance between points B(-2, 2) and C must be 4 units and the horizontal distance between points B(-2, 2) and C must be 6 units.

Now, complete the rectangle ABCD and read the coordinates of point C. As shown on the graph, C = (-2, -2).

In each of the following, the co-ordinates of the three vertices of a rectangle ABCD are given. By plotting the given points; find, in each case, the co-ordinates of the fourth vertex : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, C = (-2, -2).

(iii) After plotting the given points A(-4, -6), C(6, 0) and D(-4, 0) on a graph paper, join A with D and C with D.

From the graph it is clear that the vertical distance between the points A(-4, -6) and D(-4, 0) is 6 units and the horizontal distance between the points C(6, 0) and D(-4, 0) is 10 units. Therefore, the vertical distance between the points A(-4, -6) and B must be 10 units and the horizontal distance between the points C(6, 0) and B must be 10 units.

Now complete the rectangle ABCD and read the coordinates of point B. As shown on the graph, B = (6, -6).

In each of the following, the co-ordinates of the three vertices of a rectangle ABCD are given. By plotting the given points; find, in each case, the co-ordinates of the fourth vertex : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, B = (6, -6).

(iv) After plotting the given points B (10, 4), C (0, 4) and D (0, - 2) on a graph paper, join B with C and C with D.

From the graph it is clear that the vertical distance between the points C(0, 4) and D(0, -2) is 6 units and the horizontal distance between the points C(0, 4) and D(0, -2) is 10 units. Therefore, the vertical distance between the points B(10, 4) and A must be 6 units and the horizontal distance between the points D(0, -2) and B must be 10 units.

Now complete the rectangle ABCD and read the coordinates of point A. As shown on the graph, A = (10, -2).

In each of the following, the co-ordinates of the three vertices of a rectangle ABCD are given. By plotting the given points; find, in each case, the co-ordinates of the fourth vertex : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, A = (10, -2).

9Exercise 23(A)

A (-2, 2), B (8, 2) and C (4, -4) are the vertices of a parallelogram ABCD. By plotting the given points on a graph paper; find the co-ordinates of the fourth vertex D.

Also, from the same graph, state the co-ordinates of the mid-points of the sides AB and CD.

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Plot the points A (-2, 2), B (8, 2) and C (4, -4) on the graph paper. Join point A with B and B with C.

From the graph, it is clear that the horizontal distance between the points A (-2, 2) and B (8, 2) is 10 units and the vertical distance between the points B (8, 2) and C (4, -4) is 6 units. Therefore, the vertical distance between the points A (-2, 2) and D must be 6 units and the horizontal distance between the points C (4, -4) and D must be 10 units.

Now, complete the parallelogram ABCD and read the coordinates of point D. As shown on the graph, D = (-6, -4).

A (-2, 2), B (8, 2) and C (4, -4) are the vertices of a parallelogram ABCD. By plotting the given points on a graph paper; find the co-ordinates of the fourth vertex D. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The midpoint of AB lies exactly halfway between A(-2, 2) and B(8, 2). On the graph, this midpoint is at (3, 2), as it is 5 units from both A and B.

The midpoint of CD lies exactly halfway between C (4, -4) and B (-6, -4). On the graph, this midpoint is at (-1, -4), as it is 5 units from both C and D.

Hence, D = (-6, -4) and mid point of AB = (3, 2) and CD = (-1, -4).

10Exercise 23(A)

A (- 2, 4), C (4, 10) and D (- 2, 10) are the vertices of a square ABCD. Use the graphical method to find the co-ordinates of the fourth vertex B. Also, find :

(i) the co-ordinates of the mid-point of BC;

(ii) the co-ordinates of the mid-point of CD and

(iii) the co-ordinates of the point of intersection of the diagonals of the square ABCD.

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Plot the points A (- 2, 4), C (4, 10) and D (- 2, 10) on the graph paper. Join point A with D and D with C.

From the graph, it is clear that the horizontal distance between the points C (4, 10) and D (-2, 10) is 6 units and the vertical distance between the points A (-2, 4) and D (-2, 10) is 6 units. Therefore, the vertical distance between the points C (4, 10) and B must be 6 units and the horizontal distance between the points A (-2, 4) and B must be 6 units.

Now, complete the square ABCD and read the coordinates of point B, as shown on the graph, B = (4, 4).

A (- 2, 4), C (4, 10) and D (- 2, 10) are the vertices of a square ABCD. Use the graphical method to find the co-ordinates of the fourth vertex B. Also, find : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The midpoint of BC lies exactly halfway between B(4, 4) and C(4, 10). On the graph, this midpoint is at E(4, 7), as it is 3 units from both B and C.

The midpoint of CD lies exactly halfway between C(4, 10) and D(-2, 10). On the graph, this midpoint is at F(1, 10), as it is 3 units from both C and D.

The coordinates of the midpoint of diagonals of the square is G = (1, 7).

Hence, the co-ordinates of the mid-point of BC = (4, 7), the co-ordinates of the mid-point of CD = (1, 10) and the co-ordinates of the point of intersection of the diagonals of the square ABCD = (1, 7).

1(a)Exercise 23(B)

Line y + 7 = 0 is :

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Given:

y + 7 = 0

⇒ y = -7

The graph of y = -7 is a straight line that is parallel to the x-axis and at a distance of -7 units from it.

Hence, option 1 is the correct option.

1(b)Exercise 23(B)

A line is parallel to y-axis and at a distance of 5 units on the positive side of the x-axis. The equation of the line is :

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A line is parallel to y-axis means the equation of the line is in the form x = + a or -a units, where a is the distance from the y-axis.

If the line is at a distance of 5 units from the y-axis on the positive side, the equation will be x = 5.

Hence, option 3 is the correct option.

1(c)Exercise 23(B)

6x - 5y = 7 is the equation of a line. If x = 2 then the value of y will be :

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Given:

6x - 5y = 7

If x = 2,

⇒ 6 $\times$ 2 - 5y = 7

⇒ 12 - 5y = 7

⇒ 12 - 7 = 5y

⇒ 5 = 5y

⇒ y = $\frac{5}{5}$

⇒ y = 1

Hence, option 1 is the correct option.

1(d)Exercise 23(B)

For equation $\frac{x}{3}-\frac{y}{2}$ = 1, the value of y for x = 9 is :

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Given:

$\frac{x}{3} - \frac{y}{2} = 1$

When x = 9,

$$\begin{aligned}⇒ \frac{9}{3} - \frac{y}{2} = 1\\[1em] ⇒ 3 - \frac{y}{2} = 1\\[1em] ⇒ 3 - 1 = \frac{y}{2}\\[1em] ⇒ 2 = \frac{y}{2}\\[1em] ⇒ y = 2 \times 2\\[1em] ⇒ y = 4\end{aligned}$$

Hence, option 3 is the correct option.

1(e)Exercise 23(B)

Lines x - 4 = 0 and 3y = 1 intersect each other at point P. The co-ordinates of point P are:

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x - 4 = 0 ⇒ x = 4

This line represents a vertical line parallel to y-axis.

3y = 1 ⇒ y = $\frac{1}{3}$

This represents a horizontal line parallel to x-axis.

Since the first line has x = 4 and the second line has y = $\frac{1}{3}$, the point od intersection P is (4, $\frac{1}{3}$).

Hence, option 2 is the correct option.

2(i)Exercise 23(B)

Draw the graph for the linear equation given below :

x = 3

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x = 3

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of x = 3 is the straight line which is parallel to the y-axis at a distance of 3 units from it.

2(ii)Exercise 23(B)

Draw the graph for the linear equation given below :

x + 3 = 0

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x + 3 = 0

⇒ x = -3

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of x + 3 = 0 is the straight line which is parallel to the y-axis at a distance of -3 units from it.

2(iii)Exercise 23(B)

Draw the graph for the linear equation given below :

x - 5 = 0

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x - 5 = 0

⇒ x = 5

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of x - 5 = 0 is the straight line which is parallel to the y-axis at a distance of 5 units from it.

2(iv)Exercise 23(B)

Draw the graph for the linear equation given below :

2x - 7 = 0

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2x - 7 = 0

⇒ 2x = 7

⇒ x = $\frac{7}{2}$

⇒ x = 3.5

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of 2x - 7 = 0 is the straight line which is parallel to the y-axis at a distance of 3.5 units from it.

2(v)Exercise 23(B)

Draw the graph for the linear equation given below :

y = 4

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y = 4

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of y = 4 is the straight line which is parallel to the x-axis at a distance of 4 units from it.

2(vi)Exercise 23(B)

Draw the graph for the linear equation given below :

y + 6 = 0

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y + 6 = 0

⇒ y = - 6

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of y + 6 = 0 is the straight line which is parallel to the x-axis at a distance of -6 units from it.

2(vii)Exercise 23(B)

Draw the graph for the linear equation given below :

y - 2 = 0

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y - 2 = 0

⇒ y = 2

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of y - 2 = 0 is the straight line which is parallel to the x-axis at a distance of 2 units from it.

2(viii)Exercise 23(B)

Draw the graph for the linear equation given below :

3y + 5 = 0

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3y + 5 = 0

⇒ 3y = - 5

⇒ y = - $\frac{5}{3}$

⇒ y = - 1.6

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of 3y + 5 = 0 is the straight line which is parallel to the x-axis at a distance of - 1.6 units from it.

2(ix)Exercise 23(B)

Draw the graph for the linear equation given below :

2y - 5 = 0

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2y - 5 = 0

⇒ 2y = 5

⇒ y = $\frac{5}{2}$

⇒ y = 2.5

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of 2y - 5 = 0 is the straight line which is parallel to the x-axis at a distance of 2.5 units from it.

2(x)Exercise 23(B)

Draw the graph for the linear equation given below :

y = 0

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y = 0

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of y = 0 is the straight line which is on x-axis.

2(xi)Exercise 23(B)

Draw the graph for the linear equation given below :

x = 0

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x = 0

Draw the graph for each linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph of x = 0 is the straight line which is on y-axis.

3(i)Exercise 23(B)

Draw the graph for the linear equation given below :

y = 3x

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y = 3x

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = 3 $\times$ (-1) = -3

Let x = 0, then y = 3 $\times$ 0 = 0

Let x = 1, then y = 3 $\times$ 1 = 3

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y-303

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(ii)Exercise 23(B)

Draw the graph for the linear equation given below :

y = - x

Show SolutionHide Solution↓

y = - x

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = - (-1) = 1

Let x = 0, then y = 0 = 0

Let x = 1, then y = - 1 = - 1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y10-1

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(iii)Exercise 23(B)

Draw the graph for the linear equation given below :

y = - 2x

Show SolutionHide Solution↓

y = - 2x

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = - 2 $\times$ (-1) = 2

Let x = 0, then y = - 2 $\times$ 0 = 0

Let x = 1, then y = - 2 $\times$ 1 = - 2

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y20-2

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(iv)Exercise 23(B)

Draw the graph for the linear equation given below :

y = x

Show SolutionHide Solution↓

y = x

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = -1

Let x = 0, then y = 0

Let x = 1, then y = 1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y-101

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(v)Exercise 23(B)

Draw the graph for the linear equation given below :

5x + y = 0

Show SolutionHide Solution↓

5x + y = 0

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 5 $\times$ (-1) + y = 0 ⇒ y = 5

Let x = 0, then 5 $\times$ 0 + y = 0 ⇒ y = 0

Let x = 1, then 5 $\times$ 1 + y = 0 ⇒ y = -5

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y50-5

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(vi)Exercise 23(B)

Draw the graph for the linear equation given below :

x + 2y = 0

Show SolutionHide Solution↓

x + 2y = 0

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then (-1) + 2y = 0 ⇒ y = 0.5

Let x = 0, then 0 + 2y = 0 ⇒ y = 0

Let x = 1, then 1 + 2y = 0 ⇒ y = -0.5

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y0.50-0.5

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(vii)Exercise 23(B)

Draw the graph for the linear equation given below :

4x - y = 0

Show SolutionHide Solution↓

4x - y = 0

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 4 $\times$ (-1) - y = 0 ⇒ y = -4

Let x = 0, then 4 $\times$ 0 - y = 0 ⇒ y = 0

Let x = 1, then 4 $\times$ 1 - y = 0 ⇒ y = 4

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y-404

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(viii)Exercise 23(B)

Draw the graph for the linear equation given below :

3x + 2y = 0

Show SolutionHide Solution↓

3x + 2y = 0

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 3 $\times$ (-1) + 2y = 0 ⇒ y = 1.5

Let x = 0, then 3 $\times$ 0 + 2y = 0 ⇒ y = 0

Let x = 1, then 3 $\times$ 1 + 2y = 0 ⇒ y = -1.5

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y1.50-1.5

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
3(ix)Exercise 23(B)

Draw the graph for the linear equation given below :

x = - 2y

Show SolutionHide Solution↓

x = - 2y

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then (-1) = - 2y ⇒ y = 0.5

Let x = 0, then 0 = - 2y ⇒ y = 0

Let x = 1, then 1 = - 2y ⇒ y = - 0.5

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y0.50-0.5

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(i)Exercise 23(B)

Draw the graph for the linear equation given below :

y = 2x + 3

Show SolutionHide Solution↓

y = 2x + 3

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = 2 $\times$ (-1) + 3 ⇒ y = 1

Let x = 0, then y = 2 $\times$ 0 + 3 ⇒ y = 3

Let x = 1, then y = 2 $\times$ 1 + 3 ⇒ y = 5

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y135

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(ii)Exercise 23(B)

Draw the graph for the linear equation given below :

$y = \frac{2}{3} x - 1$

Show SolutionHide Solution↓

$y = \frac{2}{3} x - 1$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -3, then $y = \frac{2}{3} \times (-3) - 1 ⇒ y = -3$

Let x = 0, then $y = \frac{2}{3} \times 0 - 1 ⇒ y = -1$

Let x = 3, then $y = \frac{2}{3} \times 3 - 1 ⇒ y = 1$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-303
y-3-11

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(iii)Exercise 23(B)

Draw the graph for the linear equation given below :

y = -x + 4

Show SolutionHide Solution↓

y = -x + 4

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = -(-1) + 4 ⇒ y = 5

Let x = 0, then y = 0 + 4 ⇒ y = 4

Let x = 1, then y = -1 + 4 ⇒ y = 3

Step 2:

Make a table i(as given below) for the different pairs of the values of x and y:

x-101
y543

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(iv)Exercise 23(B)

Draw the graph for the linear equation given below :

$y = 4x - \frac{5}{2}$

Show SolutionHide Solution↓

$y = 4x - \frac{5}{2}$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -$\frac{3}{2} = -1.5$, then $y = 4 \times \Big(\frac{-3}{2}\Big) - \frac{5}{2} ⇒ y = -\frac{17}{2} = -8.5$

Let x = $\frac{1}{2} = 0.5$, then $y = 4 \times \frac{1}{2} - \frac{5}{2} ⇒ y = -\frac{1}{2} = -0.5$

Let x = $\frac{3}{2} = 1.5$, then $y = 4 \times \frac{3}{2} - \frac{5}{2} ⇒ y = \frac{7}{2} = 3.5$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1.50.51.5
y-8.5-0.53.5

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(v)Exercise 23(B)

Draw the graph for the linear equation given below :

$y =\frac{3}{2}x + \frac{2}{3}$

Show SolutionHide Solution↓

$y =\frac{3}{2}x + \frac{2}{3}$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -2, then $y =\frac{3}{2} \times (-2) + \frac{2}{3} ⇒ y = -2.3$

Let x = 0, then $y =\frac{3}{2} \times 0 + \frac{2}{3} ⇒ y = 0.6$

Let x = 2, then $y =\frac{3}{2} \times 2 + \frac{2}{3} ⇒ y = 3.6$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-202
y-2.30.63.6

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(vi)Exercise 23(B)

Draw the graph for the linear equation given below :

2x - 3y = 4

Show SolutionHide Solution↓

2x - 3y = 4

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -4, then 2 $\times$ (-4) - 3y = 4 ⇒ y = -4

Let x = 2, then 2 $\times$ 2 - 3y = 4 ⇒ y = 0

Let x = 5, then 2 $\times$ 5 - 3y = 4 ⇒ y = 2

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-425
y-402

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(vii)Exercise 23(B)

Draw the graph for the linear equation given below :

$\frac{x-1}{3} - \frac{y+2}{2} = 0$

Show SolutionHide Solution↓

$\frac{x-1}{3} - \frac{y+2}{2} = 0$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -5, then $\frac{-5-1}{3} - \frac{y+2}{2} = 0 ⇒ y = -6$

Let x = 1, then $\frac{1-1}{3} - \frac{y+2}{2} = 0 ⇒ y = -2$

Let x = 4, then $\frac{4-1}{3} - \frac{y+2}{2} = 0 ⇒ y = 0$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-514
y-6-20

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(viii)Exercise 23(B)

Draw the graph for the linear equation given below :

$x - 3 = \frac{2}{5}(y + 1)$

Show SolutionHide Solution↓

$x - 3 = \frac{2}{5}(y + 1)$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = 0, then $0 - 3 = \frac{2}{5}(y + 1) ⇒ y = -8.5$

Let x = 1, then $1 - 3 = \frac{2}{5}(y + 1) ⇒ y = -6$

Let x = 3, then $3 - 3 = \frac{2}{5}(y + 1) ⇒ y = -1$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x013
y-8.5-6-1

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
4(ix)Exercise 23(B)

Draw the graph for the linear equation given below :

x + 5y + 2 = 0

Show SolutionHide Solution↓

x + 5y + 2 = 0

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -2, then -2 + 5y + 2 = 0 ⇒ y = 0

Let x = 0, then 0 + 5y + 2 = 0 ⇒ y = - 0.4

Let x = 2, then 2 + 5y + 2 = 0 ⇒ y = - 0.8

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-202
y0-0.4-0.8

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the linear equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
5(i)Exercise 23(B)

Draw the graph for the equation given below :

3x + 2y = 6

Find the co-ordinates of the points where the graph (line) drawn meets the co-ordinate axes.

Show SolutionHide Solution↓

3x + 2y = 6

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 3 $\times$ (-1) + 2y = 6 ⇒ y = $\frac{9}{2} = 4.5$

Let x = 0, then 3 $\times$ 0 + 2y = 6 ⇒ y = $\frac{6}{2} = 3$

Let x = 1, then 3 $\times$ 1 + 2y = 6 ⇒ y = $\frac{3}{2} = 1.5$

Step 2: Make a table (as given below) for the different pairs of the values of x and y:

x-101
y4.531.5

Step 3: Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From the graph we get that the line meets x-axis at (2, 0) and y-axis at (0, 3)

5(ii)Exercise 23(B)

Draw the graph for the equation given below :

2x - 5y = 10

Find the co-ordinates of the points where the graph (line) drawn meets the co-ordinate axes.

Show SolutionHide Solution↓

2x - 5y = 10

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 2 $\times$ (-1) - 5y = 10 ⇒ y = $- \frac{12}{5} = -2.4$

Let x = 0, then 2 $\times$ 0 - 5y = 10 ⇒ y = $-\frac{10}{5} = -2$

Let x = 1, then 2 $\times$ 1 - 5y = 10 ⇒ y = $-\frac{8}{5} = -1.6$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y-2.4-2-1.6

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From the graph we get that the line meets x-axis at (5, 0) and y-axis at (0, -2)

5(iii)Exercise 23(B)

Draw the graph for the equation given below :

$\frac{1}{2}x + \frac{2}{3}y = 5$

Find the co-ordinates of the points where the graph (line) drawn meets the co-ordinate axes.

Show SolutionHide Solution↓

$\frac{1}{2}x + \frac{2}{3}y = 5$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -2, then $\frac{1}{2} \times (-2) + \frac{2}{3}y = 5 ⇒ y = \frac{6 \times 3}{2} = 9$

Let x = 0, then $\frac{1}{2} \times 0 + \frac{2}{3}y = 5 ⇒ y = \frac{15}{2} = 7.5$

Let x = 2, then $\frac{1}{2} \times 2 + \frac{2}{3}y = 5 ⇒ y = \frac{4 \times 3}{2} = 6$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-202
y97.56

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From the graph we get that the line meets x-axis at (10, 0) and y-axis at (0, 7.5)

5(iv)Exercise 23(B)

Draw the graph for the equation given below :

$\frac{2x - 1}{3} - \frac{y - 2}{5} = 0$

Find the co-ordinates of the points where the graph (line) drawn meets the co-ordinate axes.

Show SolutionHide Solution↓

$\frac{2x - 1}{3} - \frac{y - 2}{5} = 0$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then $\frac{2 \times (-1) - 1}{3} - \frac{y - 2}{5} = 0 ⇒ y = -3$

Let x = 0, then $\frac{2 \times 0 - 1}{3} - \frac{y - 2}{5} = 0 ⇒ y = 0.3$

Let x = 1, then $\frac{2 \times 1 - 1}{3} - \frac{y - 2}{5} = 0 ⇒ y = 3.6$

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y-30.33.6

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph for the equation given below : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From the graph we get that the line meets x-axis at (-0.1, 0) and y-axis at (0, 0.3)

6(i)Exercise 23(B)

For the linear equation, given below, draw the graph and then use the graph drawn to find the area of a triangle enclosed by the graph and the co-ordinate axes :

3x - (5 - y) = 7

Show SolutionHide Solution↓

3x - (5 - y) = 7

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 3 $\times$ (-1) - (5 - y) = 7 ⇒ y = 15

Let x = 0, then 3 $\times$ 0 - (5 - y) = 7 ⇒ y = 12

Let x = 1, then 3 $\times$ 1 - (5 - y) = 7 ⇒ y = 9

Let x = 4, then 3 $\times$ 4 - (5 - y) = 7 ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1014
y151290

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

For the linear equation, given below, draw the graph and then use the graph drawn to find the area of a triangle enclosed by the graph and the co-ordinate axes : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The area of the triangle ABO will be = $\frac{1}{2} \times base \times$ altitude

= $\frac{1}{2} \times OA \times$ OB

= $\frac{1}{2} \times 4 \times$ 12 square unit

= 24 square unit

Hence, the area of triangle = 24 square unit.

6(ii)Exercise 23(B)

For the linear equation, given below, draw the graph and then use the graph drawn to find the area of a triangle enclosed by the graph and the co-ordinate axes :

7 - 3 (1 - y) = - 5 + 2x.

Show SolutionHide Solution↓

7 - 3 (1 - y) = - 5 + 2x

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = 0, then 7 - 3 (1 - y) = - 5 + 2 $\times$ 0 ⇒ y = -3

Let x = 4.5, then 7 - 3 (1 - y) = - 5 + 2 $\times$ 4.5 ⇒ y = 0

Let x = 6, then 7 - 3 (1 - y) = - 5 + 2 $\times$ 6 ⇒ y = 1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x04.56
y-301

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

For the linear equation, given below, draw the graph and then use the graph drawn to find the area of a triangle enclosed by the graph and the co-ordinate axes : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The area of the triangle ABO will be = $\frac{1}{2} \times base \times$ altitude

= $\frac{1}{2}$ $\times$ OA $\times$ OB

= $\frac{1}{2}$ $\times$ 3 $\times$ 4.5

= 6.75 square unit

Hence, the area of triangle = 6.75 square unit.

7(i)Exercise 23(B)

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other.

y = 3x - 1
y = 3x + 2

Show SolutionHide Solution↓

First equation = y = 3x - 1

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = 3 $\times$ (-1) - 1 ⇒ y = -4

Let x = 0, then y = 3 $\times$ 0 - 1 ⇒ y = -1

Let x = 1, then y = 3 $\times$ 1 - 1 ⇒ y = 2

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y-4-12

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Second equation = y = 3x + 2

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -2, then y = 3 $\times$ (-2) + 2 ⇒ y = -4

Let x = -1, then y = 3 $\times$ (-1) + 2 ⇒ y = -1

Let x = 0, then y = 3 $\times$ 0 + 2 ⇒ y = 2

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-2-10
y-4-12

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, the two lines are parallel to each other.

7(ii)Exercise 23(B)

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other.

y = x - 3
y = - x + 5

Show SolutionHide Solution↓

First equation = y = x - 3

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = (-1) - 3 ⇒ y = - 4

Let x = 0, then y = 0 - 3 ⇒ y = - 3

Let x = 1, then y = 1 - 3 ⇒ y = - 2

Let x = 4, then y = 4 - 3 ⇒ y = 1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1014
y-4-3-21

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Second equation = y = - x + 5

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then y = - (-1) + 5 ⇒ y = 6

Let x = 0, then y = - 0 + 5 ⇒ y = 5

Let x = 1, then y = - 1 + 5 ⇒ y = 4

Let x = 4, then y = - 4 + 5 ⇒ y = 1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1014
y6541

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, the two lines are perpendicular to each other.

7(iii)Exercise 23(B)

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other.

2x - 3y = 6

$\frac{x}{2} + \frac{y}{3} = 1$

Show SolutionHide Solution↓

First equation = 2x - 3y = 6

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 2 $\times$ (-1) - 3y = 6 ⇒ y = - 2.6

Let x = 0, then 2 $\times$ (0) - 3y = 6 ⇒ y = - 2

Let x = 1, then 2 $\times$ 1 - 3y = 6 ⇒ y = - 1.3

Let x = 3, then 2 $\times$ 3 - 3y = 6 ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1013
y-2.6-2-1.30

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Second equation = $\frac{x}{2} + \frac{y}{3} = 1$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then $\frac{-1}{2} + \frac{y}{3} = 1$ ⇒ y = 4.5

Let x = 0, then $\frac{0}{2} + \frac{y}{3} = 1$ ⇒ y = 3

Let x = 1, then $\frac{1}{2} + \frac{y}{3} = 1$ ⇒ y = 1.5

Let x = 2, then $\frac{2}{2} + \frac{y}{3} = 1$ ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1012
y4.531.50

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, the two lines are perpendicular to each other.

7(iv)Exercise 23(B)

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other.

3x + 4y = 24

$\frac{x}{4} + \frac{y}{3} = 1$

Show SolutionHide Solution↓

First equation = 3x + 4y = 24

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -2, then 3 $\times$ (-2) + 4y = 24 ⇒ y = 7.5

Let x = 0, then 3 $\times$ 0 + 4y = 24 ⇒ y = 6

Let x = 2, then 3 $\times$ 2 + 4y = 24 ⇒ y = 4.5

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-202
y7.564.5

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Second equation = $\frac{x}{4} + \frac{y}{3} = 1$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then $\frac{-1}{4} + \frac{y}{3} = 1$ ⇒ y = 3.7

Let x = 0, then $\frac{0}{4} + \frac{y}{3} = 1$ ⇒ y = 3

Let x = 1, then $\frac{1}{4} + \frac{y}{3} = 1$ ⇒ y = 2.2

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y3.732.2

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

For the pair of linear equations given below, draw graphs and then state, whether the lines drawn are parallel or perpendicular to each other. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, the two lines are parallel to each other.

8Exercise 23(B)

On the same graph paper, plot the graph of y = x - 2, y = 2x + 1 and y = 4 from x = -4 to 3.

Show SolutionHide Solution↓

The given equations are y = x - 2, y = 2x + 1 and y = 4.

Make a table (as given below) for the different pairs of the values of x and y:

x-403
y = x - 2-6-21
y = 2x + 1-717
y = 4444

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

On the same graph paper, plot the graph of y = x - 2, y = 2x + 1 and y = 4 from x = -4 to 3. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
9Exercise 23(B)

On the same graph paper, plot the graphs of y = 2x - 1, y = 2x and y = 2x + 1 from x = - 2 to x = 4. Are the graphs (lines) drawn parallel to each other ?

Show SolutionHide Solution↓

The given equations are y = 2x - 1, y = 2x and y = 2x + 1.

Make a table (as given below) for the different pairs of the values of x and y:

x-204
y = 2x - 1-5-17
y = 2x-408
y = 2x + 1-319

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

On the same graph paper, plot the graphs of y = 2x - 1, y = 2x and y = 2x + 1 from x = - 2 to x = 4. Are the graphs (lines) drawn parallel to each other ? Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Yes, the lines drawn are parallel to each other.

10Exercise 23(B)

The graph of 3x + 2y = 6 meets the x-axis at point P and the y-axis at point Q. Use the graphical method to find the co-ordinates of points P and Q.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -2, then 3 $\times$ (-2) + 2y = 6 ⇒ y = 6

Let x = -1, then 3 $\times$ (-1) + 2y = 6 ⇒ y = 4.5

Let x = 0, then 3 $\times$ 0 + 2y = 6 ⇒ y = 3

Let x = 1, then 3 $\times$ 1 + 2y = 6 ⇒ y = 1.5

Let x = 2, then 3 $\times$ 2 + 2y = 6 ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-2-1012
y64.531.50

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

The graph of 3x + 2y = 6 meets the x-axis at point P and the y-axis at point Q. Use the graphical method to find the co-ordinates of points P and Q. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph intersects the x-axis at P(2,0).

The graph intersects the y-axis at Q(0,3).

Hence, the coordinates of P = (2, 0) and Q = (0, 3).

1(a)Exercise 23(C)

The inclination of a line is 60°. The slope of the line is :

Show SolutionHide Solution↓

The inclination of a line is 60°, then θ = 60°.

The slope of the line = m = tan 60° = $\sqrt3$

Hence, option 3 is the correct option.

1(b)Exercise 23(C)

For the equation 2x - 5y = 8; slope is :

Show SolutionHide Solution↓

⇒ 2x - 5y = 8

⇒ - 5y = 8 - 2x

⇒ 5y = 2x - 8

⇒ y = $\frac{2}{5}\text{x} - \frac{8}{5}$

∴ Slope = coefficient of x = $\frac{2}{5}$

Hence, option 4 is the correct option.

1(c)Exercise 23(C)

For the equation 5x - 6y = 9, the y-intercept is :

Show SolutionHide Solution↓

⇒ 5x - 6y = 9

⇒ -6y = 9 - 5x

⇒ 6y = 5x - 9

⇒ y = $\frac{5}{6}\text{x} - \frac{9}{6}$

∴ y-intercept = constant term = -$\frac{9}{6} = - \frac{3}{2}$

Hence, option 4 is the correct option.

1(d)Exercise 23(C)

If the slope of a line is -2 and its y-intercept is -7, the equation of the line is:

Show SolutionHide Solution↓

slope = -2 ⇒ m = -2

y-intercept = -7 ⇒ c = -7

∴ Equation is : y = mx + c

⇒ y = (-2)x + (-7)

⇒ y = -2x - 7

⇒ 2x + y + 7 = 0

Hence, option 1 is the correct option.

1(e)Exercise 23(C)

For the equation x - y + 1 = 0; the values of slope (m) and y-intercept (c) are :

Show SolutionHide Solution↓

The given equation : x - y + 1 = 0

⇒ y = x + 1

General form of equation: y = mx + c

m = 1, c = 1

Hence, option 1 is the correct option.

2(i)Exercise 23(C)

In the following, find the inclination of line AB :

In the following, find the inclination of line AB : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
Show SolutionHide Solution↓
In the following, find the inclination of line AB : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

MO = NO

∠ NMO = ∠ MNO

∠ MON = 90°

Let ∠ MNO = ∠ NMO = x.

As we know that sum of all angles of triangle = 180°

⇒ ∠ NMO + ∠ MNO + ∠ MON = 180°

⇒ x + x + 90° = 180°

⇒ 2x = 180° - 90°

⇒ x = $\frac{90°}{2}$

⇒ x = 45°

Hence, the inclination = 45°.

2(ii)Exercise 23(C)

In the following, find the inclination of line AB :

In the following, find the inclination of line AB : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
Show SolutionHide Solution↓
In the following, find the inclination of line AB : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

MO = NO

∠ NMO = ∠ MNO

∠ MON = 90°

Let ∠ MNO = ∠ NMO = x.

As we know that sum of all angles of triangle = 180°

⇒ ∠ NMO + ∠ MNO + ∠ MON = 180°

⇒ x + x + 90° = 180°

⇒ 2x = 180° - 90°

⇒ x = $\frac{90°}{2}$

⇒ x = 45°

Inclination = 180° - 45° = 135°

Hence, the inclination = 135°.

2(iii)Exercise 23(C)

In the following, find the inclination of line AB :

In the following, find the inclination of line AB : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
Show SolutionHide Solution↓
In the following, find the inclination of line AB : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

∠ NMO = 2x

∠ MNO = x

∠ MON = 90°

As we know that sum of all angles of triangle = 180°

⇒ ∠ NMO + ∠ MNO + ∠ MON = 180°

⇒ 2x + x + 90° = 180°

⇒ 3x = 180° - 90°

⇒ x = $\frac{90°}{3}$

⇒ x = 30°

Hence, the inclination = 30°.

3Exercise 23(C)

Write the inclination of a line which is :

(i) parallel to x-axis.

(ii) perpendicular to x-axis.

(iii) parallel to y-axis.

(iv) perpendicular to y-axis.

Show SolutionHide Solution↓

(i) A line parallel to the x-axis has an inclination of 0°, as it does not make an angle with the x-axis.

Hence, the inclination of the line = 0°.

(ii) A line perpendicular to the x-axis is parallel to the y-axis and makes a 90° angle with the x-axis.

Hence, the inclination of the line = 90°.

(iii) A line parallel to the y-axis is perpendicular to the x-axis, so its inclination is 90°.

Hence, the inclination of the line = 90°.

(iv) A line perpendicular to the y-axis is parallel to the x-axis, so its inclination is 0°.

Hence, the inclination of the line = 0°.

4Exercise 23(C)

Write the slope of the line whose inclination is:

(i) 0°

(ii) 30°

(iii) 45°

(iv) 60°

Show SolutionHide Solution↓

(i) 0°

The inclination of a line is 0°, then θ = 0°.

The slope of the line = m = tan 0° = 0

Hence, the slope of the line whose inclination is 0° is 0.

(ii) 30°

The inclination of a line is 30°, then θ = 30°.

The slope of the line = m = tan 30° = $\frac{1}{\sqrt3}$

Hence, the slope of the line whose inclination is 30° is $\frac{1}{\sqrt3}$.

(iii) 45°

The inclination of a line is 45°, then θ = 45°.

The slope of the line = m = tan 45° = 1

Hence, the slope of the line whose inclination is 45° is 1.

(iv) 60°

The inclination of a line is 60°, then θ = 60°.

The slope of the line = m = tan 60° = $\sqrt3$

Hence, the slope of the line whose inclination is 60° is $\sqrt3$.

5Exercise 23(C)

Find the inclination of the line whose slope is:

(i) 0

(ii) 1

(iii) ${\sqrt3}$

(iv) $\frac{1}{\sqrt3}$

Show SolutionHide Solution↓

(i) The slope of the line = m = 0 ⇒ tan θ = 0

⇒ tan θ = tan 0°

⇒ θ = 0°

Hence, the inclination is 0°.

(ii) The slope of the line = m = 1 ⇒ tan θ = 1

⇒ tan θ = tan 45°

⇒ θ = 45°

Hence, the inclination is 45°.

(iii) The slope of the line = m = ${\sqrt3}$ ⇒ tan θ = ${\sqrt3}$.

⇒ tan θ = tan 60°

⇒ θ = 60°

Hence, the inclination is 60°.

(iv) The slope of the line = m = $\frac{1}{\sqrt3}$ ⇒ tan θ = $\frac{1}{\sqrt3}$

⇒ tan θ = tan 30°

⇒ θ = 30°

Hence, the inclination is 30°.

6Exercise 23(C)

Write the slope of the line which is :

(i) parallel to x-axis.

(ii) perpendicular to x-axis.

(iii) parallel to y-axis.

(iv) perpendicular to y-axis.

Show SolutionHide Solution↓

(i) A line parallel to the x-axis has an inclination of 0°, as it does not make an angle with the x-axis.

Therefore, the inclination of the line is 0°.

The slope of the line = m = tan θ = tan 0° = 0

Hence, the slope of the line is 0.

(ii) A line perpendicular to the x-axis is parallel to the y-axis and makes a 90° angle with the x-axis.

Therefore, the inclination of the line is 90°.

The slope of the line = m = tan θ = tan 90° = not defined

Hence, the slope of the line is not defined.

(iii) A line parallel to the y-axis is perpendicular to the x-axis, so its inclination is 90°.

Therefore, the inclination of the line is 90°.

The slope of the line = m = tan θ = tan 90° = not defined

Hence, the slope of the line is not defined.

(iv) A line perpendicular to the y-axis is parallel to the x-axis, so its inclination is 0°.

Therefore, the inclination of the line is 0°.

The slope of the line = m = tan θ = tan 0° = 0

Hence, the slope of the line is 0.

7Exercise 23(C)

For each of the equations given below, find the slope and the y-intercept :

(i) x + 3y + 5 = 0

(ii) 3x - y - 8 = 0

(iii) 5x = 4y + 7

(iv) x = 5y - 4

(v) y = 7x - 2

(vi) 3y = 7

(vii) 4y + 9 = 0

Show SolutionHide Solution↓

(i) x + 3y + 5 = 0

⇒ 3y = -x - 5

⇒ y = -$\frac{1}{3}x - \frac{5}{3}$

∴ Slope = coefficient of x = $\frac{-1}{3}$

And, y-intercept = constant term = $\frac{-5}{3}$

Hence, the slope = $\frac{-1}{3}$ and y-intercept = $\frac{-5}{3}$.

(ii) 3x - y - 8 = 0

⇒ y = 3x - 8

∴ Slope = coefficient of x = 3

And, y-intercept = constant term = -8

Hence, the slope = 3 and y-intercept = -8.

(iii) 5x = 4y + 7

⇒ 4y = 5x - 7

⇒ y = $\frac{5}{4}$ x - $\frac{7}{4}$

∴ Slope = coefficient of x = $\frac{5}{4}$

And, y-intercept = constant term = $\frac{-7}{4}$

Hence, the slope = $\frac{5}{4}$ and y-intercept = $\frac{-7}{4}$.

(iv) x = 5y - 4

⇒ 5y = x + 4

⇒ y = $\frac{1}{5}$ x + $\frac{4}{5}$

∴ Slope = coefficient of x = $\frac{1}{5}$

And, y-intercept = constant term = $\frac{4}{5}$

Hence, the slope = $\frac{1}{5}$ and y-intercept = $\frac{4}{5}$.

(v) y = 7x - 2

∴ Slope = coefficient of x = 7

And, y-intercept = constant term = -2

Hence, the slope = 7 and y-intercept = -2.

(vi) 3y = 7

⇒ 3y = 0 $\times$ x + 7

⇒ y = 0 $\times$ x + $\frac{7}{3}$

∴ Slope = coefficient of x = 0

And, y-intercept = constant term = $\frac{7}{3}$

Hence, the slope = 0 and y-intercept = $\frac{7}{3}$.

(vii) 4y + 9 = 0

⇒ 4y = 0 $\times$ x - 9

⇒ y = 0 $\times$ x - $\frac{9}{4}$

∴ Slope = coefficient of x = 0

And, y-intercept = constant term = $\frac{-9}{4}$

Hence, the slope = 0 and y-intercept = $\frac{-9}{4}$.

8Exercise 23(C)

Find the equation of the line, whose :

(i) slope = 2 and y-intercept = 3

(ii) slope = 5 and y-intercept = - 8

(iii) slope = - 4 and y-intercept = 2

(iv) slope = - 3 and y-intercept = - 1

(v) slope = 0 and y-intercept = - 5

(vi) slope = 0 and y-intercept = 0

Show SolutionHide Solution↓

(i) slope = 2 ⇒ m = 2

y-intercept = 3 ⇒ c = 3

∴ Equation is : y = mx + c

⇒ y = 2x + 3

Hence, the equation of the line is y = 2x + 3.

(ii) slope = 5 ⇒ m = 5

y-intercept = -8 ⇒ c = -8

∴ Equation is : y = mx + c

⇒ y = 5x - 8

Hence, the equation of the line is y = 5x - 8.

(iii) slope = -4 ⇒ m = -4

y-intercept = 2 ⇒ c = 2

∴ Equation is : y = mx + c

⇒ y = -4x + 2

⇒ 4x + y = 2

Hence, the equation of the line is 4x + y = 2.

(iv) slope = -3 ⇒ m = -3

y-intercept = -1 ⇒ c = -1

∴ Equation is : y = mx + c

⇒ y = -3x - 1

⇒ 3x + y + 1 = 0

Hence, the equation of the line is 3x + y + 1 = 0.

(v) slope = 0 ⇒ m = 0

y-intercept = - 5 ⇒ c = - 5

∴ Equation is : y = mx + c

⇒ y = 0 $\times$ x - 5

⇒ y + 5 = 0

Hence, the equation of the line is y + 5 = 0.

(vi) slope = 0 ⇒ m = 0

y-intercept = 0 ⇒ c = 0

∴ Equation is : y = mx + c

⇒ y = 0 $\times$ x + 0

⇒ y = 0

Hence, the equation of the line is y = 0.

9Exercise 23(C)

Draw the line 3x + 4y = 12 on a graph paper. From the graph paper, read the y-intercept of the line.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = 0, then 3 $\times$ 0 + 4y = 12 ⇒ y = 3

Let x = 1, then 3 $\times$ 1 + 4y = 12 ⇒ y = 2.2

Let x = 4, then 3 $\times$ 4 + 4y = 12 ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x014
y32.20

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the line 3x + 4y = 12 on a graph paper. From the graph paper, read the y-intercept of the line. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From the graph, y-intercept of the line = OB = 3.

Hence, y-intercept of the line = 3.

10Exercise 23(C)

Draw the line 2x - 3y - 18 = 0 on a graph paper. From the graph paper, read the y-intercept of the line.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = 0, then 2 $\times$ 0 - 3y - 18 = 0 ⇒ y = -6

Let x = 3, then 2 $\times$ 3 - 3y - 18 = 0 ⇒ y = -4

Let x = 6, then 2 $\times$ 6 - 3y - 18 = 0 ⇒ y = -2

Let x = 9, then 2 $\times$ 9 - 3y - 18 = 0 ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x0369
y-6-4-20

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the line 2x - 3y - 18 = 0 on a graph paper. From the graph paper, read the y-intercept of the line. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From the graph, y-intercept of the line = OB = -6.

Hence, y-intercept of the line = -6.

1(a)Test Yourself

For point P(-5, 4):

Show SolutionHide Solution↓

Given, point P(-5, 4)

Abscissa (x-coordinate): -5

Ordinate (y-coordinate): 4

Hence, option 2 is the correct option.

1(b)Test Yourself

If the perpendicular distance of a point P from the x-axis is 5 unit then the point P has

Show SolutionHide Solution↓

As we know that the distance of a point from the X-axis is the absolute value of its y-coordinate.

So, if perpendicular distance of a point from the x-axis is 5 units. Then the y-coordinate can be 5 or -5.

Hence, option 4 is the correct option.

1(c)Test Yourself

A point lies on y-axis at a distance of 2 unit from x-axis. Its co-ordinates are :

Show SolutionHide Solution↓

If a point lies on the y‑axis, its x‑coordinate is 0.

If it’s at a distance of 2 units from the x‑axis, that means its y-coordinate is either +2 or −2 (since distance ignores sign).

Its co-ordinates are (0, 2) or (0, -2).

Hence, option 4 is the correct option.

1(d)Test Yourself

Three vertices of a square ABCD are A(2, 0), B(-3, 0) and C(-3, -5). Its fourth vertex D is:

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The points are shown on the graph below:

Three vertices of a square ABCD are A(2, 0), B(-3, 0) and C(-3, -5). Its fourth vertex D is: Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Steps of construction :

  1. Plot points A(2, 0), B(-3, 0) and C(-3, -5) on graph.

  2. Measure AB.

  3. Mark point D such that it is at a distance AB from points A and C.

  4. Join AB, BC, CD and DA.

From graph,

The co-ordinates of fourth vertex D is (2, -5).

Hence, option 2 is the correct option.

1(e)Test Yourself

Statement 1: In the given diagram, OAB is an equilateral triangle.

Co-ordinates of the vertex B = (4, 4)

In the given diagram, OAB is an equilateral triangle. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Statement 2: B = (4, $4\sqrt{3}$)

Show SolutionHide Solution↓

Given equilateral triangle OAB.

OA = OB = AB = 8 units.

Draw BD ⊥ OA.

In an equilateral triangle, a perpendicular drawn from one of the vertices to the opposite side bisects the side.

∴ OD = $\frac{1}{2}$ x OA = ​$\frac{1}{2}$ x 8 = 4.

In right angle triangle OBD,

By pythagoras theorem,

⇒ OB2 = OD2 + BD2

⇒ 82 = 42 + BD2

⇒ 64 = 16 + BD2

⇒ BD2 = 64 - 16

⇒ BD2 = 48

⇒ BD = $\sqrt{48}$

⇒ BD = $4\sqrt{3}$

In the given diagram, OAB is an equilateral triangle. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From graph,

Co-ordinates of O = (0, 0)

Co-ordinates of A = (8, 0)

As, OD = 4 units and BD = $4\sqrt{3}$ units.

Co-ordinates of B = (4, $4\sqrt{3}$).

∴ Statement 1 is false, and statement 2 is true.

Hence, option 4 is the correct option.

1(f)Test Yourself

Statement 1: The vertex B of square OABC with each side 4 units lies in the fourth quadrant and its side are along the co-ordinate axes. The co-ordinate of vertex B are (4, -4).

Statement 2: B = (4, 4)

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The vertex B of square OABC with each side 4 units lies in the fourth quadrant and its side are along the co-ordinate axes. The co-ordinate of vertex B are (4, -4). Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Vertex B lies in the fourth quadrant. The square's sides are along the coordinate axes, so one vertex, O, is at the origin (0, 0).

The side length is 4 units.

With O at (0, 0), the other two vertices on the axes must be A (4, 0) on the positive x-axis and C (0, -4) on the negative y-axis.

The fourth quadrant is where the x-coordinates are positive and the y-coordinates are negative.

Vertex B is located at the point where the line extending 4 units to the right from C (0, -4) intersects with the line extending 4 units down from A (4, 0), which is (4, -4).

⇒ B = (4, –4).

∴ Statement 1 is true, and statement 2 is false.

Hence, option 3 is the correct option.

1(g)Test Yourself

Assertion (A): PQR is an equilateral triangle. The co-ordinates of point Q are (0, $2\sqrt{2}$).

PQR is an equilateral triangle. The co-ordinates of point Q are Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Reason (R): In ΔOPQ,

OQ2 = PQ2 - OP2 = 42 - 22 = 12.

Show SolutionHide Solution↓

The coordinates of R(0, 2) and P(0, -2).

Using distance formula,

Distance between two points = $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$

PR = $\sqrt{(0 - 0)^2 + (-2 - 2)^2} = \sqrt{(-4)^2} = \sqrt{16} = 4$ units.

Given equilateral triangle PQR.

∴ PQ = QR = PR = 4 units.

In an equilateral triangle, a perpendicular drawn from one of the vertices to the opposite side bisects the side.

∴ OP = $\frac{1}{2}$ x PR = ​$\frac{1}{2}$ x 4 = 2 units.

In right angle triangle OPQ,

By pythagoras theorem,

⇒ QP2 = OP2 + OQ2

⇒ OQ2 = QP2 - OP2

⇒ OQ2 = 42 - 22

⇒ OQ2 = 16 - 4

⇒ OQ2 = 12

⇒ OQ = $\sqrt{12}$

⇒ OQ = $2\sqrt{3}$

Since, OQ = $2\sqrt{3}$ units and Q lies on x-axis.

Co-ordinates of Q = ($2\sqrt{3}$, 0).

∴ A is false, but R is true.

Hence, option 2 is the correct option.

1(h)Test Yourself

Assertion (A): (2x - 3y, 8) = (2, x + 2y)

⇒ x = 1 and y = -2

Reason (R): 2x - 3y = 2 and 8 = x + 2y

which on solving give x = 4 and y = 2.

Show SolutionHide Solution↓

Given, (2x - 3y, 8) = (2, x + 2y)

Thus,

2x - 3y = 2 ........(1)

x + 2y = 8 ........(2)

So, reason (R) is true.

Multiplying equation (2) by 2, we get :

⇒ 2(x + 2y) = 2 × 8

⇒ 2x + 4y = 16 ........(3)

Subtracting equation (1) from (3), we get :

⇒ 2x + 4y - (2x - 3y) = 16 - 2

⇒ 2x - 2x + 4y + 3y = 14

⇒ 7y = 14

⇒ y = $\frac{14}{7}$ = 2.

Substituting the value y = 2 in first equation,

⇒ 2x - 3 x 2 = 2

⇒ 2x - 6 = 2

⇒ 2x = 2 + 6

⇒ 2x = 8

⇒ x = $\frac{8}{2}$ = 4.

Hence, the value of x = 4 and y = 2.

∴ A is false, but R is true.

Hence, option 2 is the correct option.

2(i)Test Yourself

By plotting the following points on the same graph paper, check whether they are collinear or not :

(3, 5), (1, 1) and (0, -1)

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(3, 5), (1, 1) and (0, -1)

By plotting the following points on the same graph paper, check whether they are collinear or not : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

As shown in the figure, all three points lie on the same straight line.

Hence, the points are collinear.

2(ii)Test Yourself

By plotting the following points on the same graph paper, check whether they are collinear or not :

(-2, -1), (-1, -4) and (-4, 1)

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(-2, -1), (-1, -4) and (-4, 1)

By plotting the following points on the same graph paper, check whether they are collinear or not : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

As shown in the figure, all three points do not lie on the same straight line.

Hence, the points are not collinear.

3Test Yourself

Plot the point A (5, -7). From point A, draw AM perpendicular to x-axis and AN perpendicular to y-axis. Write the co-ordinates of points M and N.

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Given point : A (5, -7)

AM is perpendicular to the x-axis.

AN is perpendicular to the y-axis.

Plot the point A (5, -7). From point A, draw AM perpendicular to x-axis and AN perpendicular to y-axis. Write the co-ordinates of points M and N. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

The graph intersects the x-axis at M(5, 0).

The graph intersects the y-axis at N(0, -7).

Hence, the coordinates of the points are M = (5, 0) and N = (0, -7).

4Test Yourself

In square ABCD; A = (3, 4), B = (-2, 4) and C = (-2, -1). By plotting these points on a graph paper, find the co-ordinates of vertex D. Also, find the area of the square.

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Plot the points A = (3, 4), B = (-2, 4) and C = (-2, -1) on the graph paper. Join point A with B and B with C.

From the graph, it is clear that the horizontal distance between the points A (3, 4) and B (-2, 4) is 5 units and the vertical distance between the points B (-2, 4) and C (-2, -1) is 5 units. Therefore, the vertical distance between the points A (3, 4) and D must be 5 units and the horizontal distance between the points C (-2, -1) and D must be 5 units.

Now, complete the square ABCD and read the coordinates of point D, as shown on the graph, D = (3, -1).

In square ABCD; A = (3, 4), B = (-2, 4) and C = (-2, -1). By plotting these points on a graph paper, find the co-ordinates of vertex D. Also, find the area of the square. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Area of the square ABCD = AD x CD

= 5 x 5 square units

= 25 square units

Hence, the coordinates of D = (3, -1) and the area of the square = 25 square units.

5Test Yourself

In rectangle OABC; point O is the origin, OA = 10 units along x-axis and AB = 8 units. Find the co-ordinates of vertices A, B and C.

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Given that in rectangle OABC, point O is the origin and OA = 10 units along x-axis, therefore we have O(0, 0) and A(10, 0).

It is also given that AB = 8 units. Since AB is perpendicular to OA (as OABC is a rectangle), the line through A is a vertical line and it meets B at B(10, 8).

Through point B, draw a horizontal line (parallel to x-axis) that meets the y-axis at y = 8. This gives the coordinates of point C: (0, 8).

In rectangle OABC; point O is the origin, OA = 10 units along x-axis and AB = 8 units. Find the co-ordinates of vertices A, B and C. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Thus, the vertices of rectangle OABC are: O(0, 0), A(10, 0), B(10, 8) and C(0, 8)

Hence, the coordinates of the vertices are A = (10, 0), B = (10, 8) and C = (0, 8).

6Test Yourself

Draw the graph of equation x + 2y - 3 = 0. From the graph, find :

(i) x1, the value of x, when y = 3

(ii) x2, the value of x, when y = -2.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then (-1) + 2y - 3 = 0 ⇒ y = 2

Let x = 0, then 0 + 2y - 3 = 0 ⇒ y = 1.5

Let x = 1, then 1 + 2y - 3 = 0 ⇒ y = 1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y21.51

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line AB passing through the points plotted on the graph.

Draw the graph of equation x + 2y - 3 = 0. From the graph, find : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

(i) To find x1, the value of x, when y = 3:

Through the point y = 3, draw a horizontal straight line which meets the line AB at point C. Through point C, draw a vertical line which meets the x-axis at x = -3.

Hence, the value of x, when y = 3 is -3 , i.e, x1 = -3.

(ii) To find x2, the value of x, when y = -2:

Through the point y = -2, draw a horizontal straight line which meets the line AB at point D. Now, through point D, draw a vertical line which meets the y-axis at x = 7.

Hence, the value of x, when y = -2 is 7 , i.e, x2 = 7.

7Test Yourself

Draw the graph of equation 3x - 4y = 12. Use the graph drawn to find :

(i) y1, the value of y, when x = 4

(ii) y2, the value of y, when x = 0.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -2, then 3 $\times$ (-2) - 4y = 12 ⇒ y = -4.5

Let x = 1, then 3 $\times$ 1 - 4y = 12 ⇒ y = -2.2

Let x = 2, then 3 $\times$ 2 - 4y = 12 ⇒ y = -1.5

Let x = 4, then 3 $\times$ 4 - 4y = 12 ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-2124
y-4.5-2.2-1.50

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph of equation 3x - 4y = 12. Use the graph drawn to find : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

(i) To find y1, the value of y, when x = 4:

Through the point x = 4, draw a horizontal line which meets the y-axis at y = 0.

Hence, the value of y, when x = 4 is 0 , i.e, y1 = 0.

(ii) To find y2, the value of y, when x = 0:

Through the point x = 0, draw a vertical line which meets the y-axis at x = -3.

Hence, the value of y, when x = 0 is -3 , i.e, y2 = -3.

8Test Yourself

Draw the graph of equation $\frac{x}{4} + \frac{y}{5} = 1$. Use the graph drawn to find :

(i) x1, the value of x, when y = 10

(ii) y1, the value of y, when x = 8.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -4, then $\frac{-4}{4} + \frac{y}{5} = 1$ ⇒ y = 10

Let x = 0, then $\frac{0}{4} + \frac{y}{5} = 1$ ⇒ y = 5

Let x = 4, then $\frac{4}{4} + \frac{y}{5} = 1$ ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x- 404
y1050

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line AB passing through the points plotted on the graph.

Draw the graph of equation x/4 + y/5 = 1. Use the graph drawn to find : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

(i) To find x1, the value of x, when y = 10:

Through the point y = 10, draw a horizontal straight line which meets the line AB at point C.

Through point C, draw a vertical line which meets the x-axis at x = -4.

Hence, the value of x, when y = 10 is -4 , i.e, x1 = -4.

(ii) To find y1, the value of y, when x = 8:

Through the point x = 8, draw a vertical line which meets the line AB at point D.

Now, through point D, draw a horizontal line which meets the y-axis at y = -5.

Hence, the value of y, when x = 8 is -5 , i.e, y1 = -5.

9Test Yourself

Use the graphical method to show that the straight lines given by the equations $x + y = 2, x - 2y = 5$ and $\frac{x}{3} + y = 0$ pass through the same point.

Show SolutionHide Solution↓

First equation : x + y = 2

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then (-1) + y = 2 ⇒ y = 3

Let x = 0, then 0 + y = 2 ⇒ y = 2

Let x = 1, then 1 + y = 2 ⇒ y = 1

Let x = 3, then 3 + y = 2 ⇒ y = -1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1013
y321-1

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Second equation : x - 2y = 5

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then (-1) - 2y = 5 ⇒ y = -3

Let x = 0, then 0 - 2y = 5 ⇒ y = -2.5

Let x = 1, then 1 - 2y = 5 ⇒ y = -2

Let x = 3, then 3 - 2y = 5 ⇒ y = -1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1013
y-3-2.5-2-1

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Third equation : $\frac{x}{3} + y = 0$

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -3, then $\frac{-3}{3} + y = 0$ ⇒ y = 1

Let x = 0, then $\frac{0}{3} + y = 0$ ⇒ y = 0

Let x = 3, then $\frac{3}{3} + y = 0$ ⇒ y = -1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-303
y10-1

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Use the graphical method to show that the straight lines given by the equations x + y = 2, x - 2y = 5 and x/3 + y = 0 pass through the same point. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

Hence, the three straight lines pass through the same point.

10Test Yourself

Draw the graph of line x + y = 5. Use the graph paper drawn to find the inclination and the y-intercept of the line.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = (-1), then (-1) + y = 5 ⇒ y = 6

Let x = 0, then 0 + y = 5 ⇒ y = 5

Let x = 1, then 1 + y = 5 ⇒ y = 4

Let x = 5, then 5 + y = 5 ⇒ y = 0

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-1015
y6540

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph of line x + y = 5. Use the graph paper drawn to find the inclination and the y-intercept of the line. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

From the graph, inclination of the line = θ = 135° and y-intercept of the line = OB = 5.

Hence, inclination = 135° and y-intercept of the line = 5.

11Test Yourself

Draw the graph of line 2x + y = 5.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = -1, then 2 $\times$ (-1) + y = 5 ⇒ y = 7

Let x = 0, then 2 $\times$ 0 + y = 5 ⇒ y = 5

Let x = 1, then 2 $\times$ 1 + y = 5 ⇒ y = 3

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x-101
y753

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line passing through the points plotted on the graph.

Draw the graph of line 2x + y = 5. Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.
12Test Yourself

Draw the graph of line 4x - y = 5. Use this graph to find :

(i) x1, the value of x when y = 3.

(ii) y1, the value of y, when x = 3.

Show SolutionHide Solution↓

Step 1:

Give at least three suitable values to the variable x and find the corresponding values of y.

Let x = 4, then 4 $\times$ (4) - y = 5 ⇒ y = 11

Let x = 3.5, then 4 $\times$ 3.5 - y = 5 ⇒ y = 9

Let x = 1, then 4 $\times$ 1 - y = 5 ⇒ y = -1

Step 2:

Make a table (as given below) for the different pairs of the values of x and y:

x43.53
y1197

Step 3:

Plot the points, from the table, on a graph paper and then draw a straight line AB passing through the points plotted on the graph.

Draw the graph of line 4x - y = 5. Use this graph to find : Co-ordinate Geometry, Concise Mathematics Solutions ICSE Class 9.

(i) To find x1, the value of x, when y = 3:

Through the point y = 3, draw a horizontal straight line which meets the line AB at point C.

Through point C, draw a vertical line which meets the x-axis at x = 2.

Hence, the value of x, when y = 3 is 2 , i.e, x1 = 2.

(ii) To find y1, the value of y, when x = 3:

Through the point x = 3, draw a vertical line which meets the line AB at point D.

Through point D, draw a horizontal line which meets the y-axis at y = 7.

Hence, the value of y, when x = 3 is 7 , i.e, y1 = 7.

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