Section & Mid-Point Formulae

ICSE Class 10 Mathematics · RS Aggarwal Mathematics · 69 solved questions

Exercise
Marks
1(i)Exercise 13

Find the co-ordinates of point P which divides the line segment joining A(-2, -7) and B(6, 1) in the ratio 5 : 3.

Show SolutionHide Solution↓

Let point P be (x, y).

Given,

m1 : m2 = 5 : 3

Find the co-ordinates of point P which divides the line segment joining A(-2, -7) and B(6, 1) in the ratio 5 : 3. Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{5 \times 6 + 3 \times -2}{5 + 3}, \frac{5 \times 1 + 3 \times -7}{5 + 3}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{30 - 6}{8}, \frac{5 - 21}{8}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{24}{8}, \frac{-16}{8}\Big) \\[1em] \Rightarrow (x, y) = (3, -2).\end{aligned}$$

Hence, the coordinates of P are (3, -2).

1(ii)Exercise 13

The line segment joining the points A(4, -3) and B(4, 2) is divided by the point P such that AP : AB = 2 : 5. Find the co-ordinates of P.

Show SolutionHide Solution↓

Let point P be (x, y).

The line segment joining the points A(4, -3) and B(4, 2) is divided by the point P such that AP : AB = 2 : 5. Find the co-ordinates of P. Reflection, RSA Mathematics Solutions ICSE Class 10.

$$\begin{aligned}\Rightarrow \frac{AP}{AB} = \frac{2}{5} \\[1em] \Rightarrow \frac{AP}{AP + PB} = \frac{2}{5} \\[1em] \Rightarrow 5AP = 2AP + 2PB \\[1em] \Rightarrow 3AP = 2PB \\[1em] \Rightarrow \frac{AP}{PB} = \frac{2}{3} \\[1em] \Rightarrow AP : PB = 2 : 3.\end{aligned}$$

m1 : m2 = AP : PB = 2 : 3.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{2 \times 4+ 3 \times 4}{2 + 3}, \frac{2 \times 2 + 3 \times -3}{2 + 3}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{8 + 12}{5}, \frac{4 - 9}{5}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{20}{5}, \frac{-5}{5}\Big) \\[1em] \Rightarrow (x, y) = (4, -1).\end{aligned}$$

Hence, the coordinates of P are (4, -1).

2Exercise 13

P(1, -2) is a point on the line segment A(3, -6) and B(x, y) such that AP : PB is equal to 2 : 3. Find the co-ordinates of B.

Show SolutionHide Solution↓

Given,

m1 : m2 = 2 : 3

By section-formula,

x = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

P(1, -2) is a point on the line segment A(3, -6) and B(x, y) such that AP : PB is equal to 2 : 3. Find the co-ordinates of B. Reflection, RSA Mathematics Solutions ICSE Class 10.

Substituting values we get :

$$\begin{aligned}\Rightarrow 1 = \Big(\frac{2 \times x + 3 \times 3}{2 + 3}\Big) \\[1em] \Rightarrow 1 = \Big(\frac{2x + 9}{5}\Big) \\[1em] \Rightarrow 5 = 2x + 9 \\[1em] \Rightarrow 5 - 9 = 2x \\[1em] \Rightarrow -4 = 2x \\[1em] \Rightarrow x = \frac{-4}{2} \\[1em] \Rightarrow x = -2.\end{aligned}$$

By section-formula,

y = $\Big(\frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow -2 = \Big(\frac{2 \times y + 3 \times -6}{2 + 3}\Big) \\[1em] \Rightarrow -2 = \Big(\frac{2y - 18}{5}\Big) \\[1em] \Rightarrow -10 = 2y - 18 \\[1em] \Rightarrow -10 + 18 = 2y \\[1em] \Rightarrow 8 = 2y \\[1em] \Rightarrow y = \frac{8}{2} \\[1em] \Rightarrow y = 4.\end{aligned}$$

Hence, the coordinates of B are (-2, 4).

3Exercise 13

Find a point P on the line segment joining A(14, -5) and B(-4, 4), which is twice as far from A as from B.

Show SolutionHide Solution↓

Let point P be (x, y).

P(1, -2) is a point on the line segment A(3, -6) and B(x, y) such that AP : PB is equal to 2 : 3. Find the co-ordinates of B. Reflection, RSA Mathematics Solutions ICSE Class 10.

Since, point P is twice as far from A as from B.

⇒ AP = 2BP

⇒ $\frac{AP}{BP} = \frac{2}{1}$

⇒ AP : BP = 2 : 1.

⇒ m1 : m2 = AP : PB = 2 : 1

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{2 \times -4+ 1 \times 14}{2 + 1}, \frac{2 \times 4 + 1 \times -5}{2 + 1}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{-8 + 14}{3}, \frac{8 - 5}{3}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{6}{3}, \frac{3}{3}\Big) \\[1em] \Rightarrow (x, y) = (2, 1).\end{aligned}$$

Hence, the coordinates of P are (2, 1).

4Exercise 13

Find the co-ordinates of the points of trisection of the line segment joining the points A(5, -3) and B(2, -9).

Show SolutionHide Solution↓

Let point P is the first point of trisection, meaning it divides the segment AB internally in the ratio m1 : m2 = 1 : 2

Find the co-ordinates of the points of trisection of the line segment joining the points A(5, -3) and B(2, -9). Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow P(x, y) = \Big(\frac{1 \times 2 + 2 \times 5}{1 + 2}, \frac{1 \times -9 + 2 \times -3}{1 + 2}\Big) \\[1em] \Rightarrow P(x, y) = \Big(\frac{2 + 10}{3}, \frac{-9 - 6}{3}\Big) \\[1em] \Rightarrow P(x, y) = \Big(\frac{12}{3}, \frac{-15}{3}\Big) \\[1em] \Rightarrow P(x, y) = (4, -5).\end{aligned}$$

Let point Q is the second point of trisection, meaning it divides the segment AB internally in the ratio m1 : m2 = 2 : 1

Substituting values we get :

$$\begin{aligned}\Rightarrow Q(a, b) = \Big(\frac{2 \times 2 + 1 \times 5}{2 + 1}, \frac{2 \times -9 + 1 \times -3}{2 + 1}\Big) \\[1em] \Rightarrow Q(a, b) = \Big(\frac{4 + 5}{3}, \frac{-18 - 3}{3}\Big) \\[1em] \Rightarrow Q(a, b) = \Big(\frac{9}{3}, \frac{-21}{3}\Big) \\[1em] \Rightarrow Q(a, b) = (3, -7).\end{aligned}$$

Hence, the coordinates of trisection are P(4, -5) and Q(3, -7).

5Exercise 13

Find the co-ordinates of the mid-point of the line segment joining :

(i) A(5, 7) and B(-3, -1)

(ii) P(-5, -8) and Q(3, 4)

Show SolutionHide Solution↓

(i) Let mid-point of the line segment joining AB be P(x,y).

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{5 + (-3)}{2}, \frac{7 + (-1)}{2}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{2}{2}, \frac{6}{2}\Big) \\[1em] \Rightarrow (x, y) = (1, 3).\end{aligned}$$

Hence, the coordinates of mid-point are (1, 3).

(ii) Let mid-point of the line segment joining PQ be B(x,y).

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{-5 + 3}{2}, \frac{-8 + 4}{2}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{-2}{2}, \frac{-4}{2}\Big) \\[1em] \Rightarrow (x, y) = (-1, -2).\end{aligned}$$

Hence, the coordinates of mid-point are (-1, -2).

6Exercise 13

The line segment joining A(-3, 1) and B(7, -5) is a diameter of a circle whose centre is C. Find the co-ordinates of the centre C.

Show SolutionHide Solution↓

Since the line segment joining points A and B is the diameter of the circle, the centre of the circle must be the mid-point of the diameter AB.

The line segment joining A(-3, 1) and B(7, -5) is a diameter of a circle whose centre is C. Find the co-ordinates of the centre C. Reflection, RSA Mathematics Solutions ICSE Class 10.

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow C(x, y) = \Big(\frac{-3 + 7}{2}, \frac{1 + (-5)}{2}\Big) \\[1em] \Rightarrow C(x, y) = \Big(\frac{4}{2}, \frac{-4}{2}\Big) \\[1em] \Rightarrow C(x, y) = (2, -2).\end{aligned}$$

Hence, the coordinates of centre (C) are (2, -2).

7Exercise 13

A(10, 5), B(6, -3) and C(2, 1) are the vertices of a ΔABC. L is the mid-point of AB and M is the mid-point of AC. Write down the co-ordinates of L and M. Show that $LM = \frac{1}{2} BC.$

Show SolutionHide Solution↓

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

L is the mid-point of AB.

A(10, 5), B(6, -3) and C(2, 1) are the vertices of a ΔABC. L is the mid-point of AB and M is the mid-point of AC. Write down the co-ordinates of L and M. Show that. Reflection, RSA Mathematics Solutions ICSE Class 10.

Substituting values we get :

$$\begin{aligned}\Rightarrow L = \Big(\frac{10 + 6}{2}, \frac{5 + (-3)}{2}\Big) \\[1em] \Rightarrow L = \Big(\frac{16}{2}, \frac{2}{2}\Big) \\[1em] \Rightarrow L = (8, 1).\end{aligned}$$

Given,

M is the mid-point of AC.

Substituting values we get :

$$\begin{aligned}\Rightarrow M = \Big(\frac{10 + 2}{2}, \frac{5 + 1}{2}\Big) \\[1em] \Rightarrow M = \Big(\frac{12}{2}, \frac{6}{2}\Big) \\[1em] \Rightarrow M = (6, 3).\end{aligned}$$

By distance formula,

d = $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$

Substituting values we get :

$$\begin{aligned}LM = \sqrt{(6 - 8)^2 + (3 - 1)^2} \\[1em] = \sqrt{(-2)^2 + (2)^2} \\[1em] = \sqrt{4 + 4} \\[1em] = \sqrt{8} = 2\sqrt{2}. \\[1em] BC = \sqrt{(2 - 6)^2 + (1 - (-3))^2} \\[1em] = \sqrt{(-4)^2 + (4)^2} \\[1em] = \sqrt{16 + 16} \\[1em] = \sqrt{32} \\[1em] = \sqrt{16 \times 2} \\[1em] = 4\sqrt{2} \\[1em] = 2 \times 2\sqrt{2} \\[1em] = 2 \times LM.\end{aligned}$$

Thus, BC = 2LM or LM = $\frac{1}{2}BC.$

Hence, proved that $LM = \frac{1}{2}BC$.

8Exercise 13

The mid-point of the line segment joining A(p, 5) and B(3, q) is M(-1, 4). Find the values of p and q.

Show SolutionHide Solution↓

Given,

Mid-point of the line segment joining A(p, 5) and B(3, q) is M(-1, 4).

The mid-point of the line segment joining A(p, 5) and B(3, q) is M(-1, 4). Find the values of p and q. Reflection, RSA Mathematics Solutions ICSE Class 10.

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (-1, 4) = \Big(\frac{p + 3}{2}, \frac{5 + q}{2} \Big) \\[1em] \Rightarrow (-1, 4) = \Big(\frac{p + 3}{2}, \frac{5 + q}{2}\Big) \\[1em] \Rightarrow -1 = \frac{p + 3}{2} \text{ and } 4 = \frac{5 + q}{2} \\[1em] \Rightarrow p + 3 = -2 \text{ and } 5 + q = 8 \\[1em] \Rightarrow p = -2 - 3 \text{ and } q = 8 - 5 \\[1em] \Rightarrow p = -5 \text{ and } q = 3.\end{aligned}$$

Hence, p = -5 and q = 3.

9Exercise 13

The centre of a circle is C(-2, 3) and one end of a diameter PQ is P(2, -4). Find the co-ordinates of Q.

Show SolutionHide Solution↓

Since PQ is the diameter of the circle and C is the center, C must be the mid-point of the segment PQ.

Let coordinates of Q be (x1, y1).

The centre of a circle is C(-2, 3) and one end of a diameter PQ is P(2, -4). Find the co-ordinates of Q. Reflection, RSA Mathematics Solutions ICSE Class 10.

By using mid-point formula,

x-coordinate = $\Big(\frac{x_1 + x_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow -2 = \Big(\frac{2 + x_1}{2}\Big) \\[1em] \Rightarrow -4 = 2 + x_1 \\[1em] \Rightarrow -4 - 2 = x_1 \\[1em] \Rightarrow x_1 = -6.\end{aligned}$$

By using mid-point formula,

y-coordinate = $\Big(\frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow 3 = \Big(\frac{-4 + y_1}{2}\Big) \\[1em] \Rightarrow 6 = -4 + y_1 \\[1em] \Rightarrow 6 + 4 = y_1 \\[1em] \Rightarrow y_1 = 10.\end{aligned}$$

Q = (x1, y1) = (-6, 10).

Hence, coordinates of Q are (-6, 10).

10Exercise 13

The point P(-4, 1) divides the line segment joining the points A(2, -2) and B in the ratio 3 : 5. Find the co-ordinates of point B.

Show SolutionHide Solution↓

Let coordinates of B be (a, b).

Point P(-4, 1) divides the line segment joining A(2, -2) and B(a, b) in the ratio 3 : 5.

The point P(-4, 1) divides the line segment joining the points A(2, -2) and B in the ratio 3 : 5. Find the co-ordinates of point B. Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (-4, 1) = \Big(\frac{3a + 5(2)}{3 + 5}, \frac{3b + 5(-2)}{3 + 5}\Big) \\[1em] \Rightarrow (-4, 1) = \Big(\frac{3a + 10}{8}, \frac{3b - 10}{8}\Big) \\[1em] \Rightarrow -4 = \Big(\frac{3a + 10}{8}\Big) \text{ and } 1 = \Big(\frac{3b - 10}{8}\Big) \\[1em] \Rightarrow -32 = 3a + 10 \text{ and } 8 = 3b - 10 \\[1em] \Rightarrow -32 - 10 = 3a \text{ and } 8 + 10 = 3b \\[1em] \Rightarrow -42 = 3a \text{ and } 18 = 3b \\[1em] \Rightarrow a = \frac{-42}{3} \text{ and } b = \frac{18}{3} \\[1em] \Rightarrow a = -14 \text{ and }b = 6 .\end{aligned}$$

B = (a, b) = (-14, 6).

Hence, coordinates of B(-14, 6).

11Exercise 13

In what ratio does the point P(2, -5) divide the join of A(-3, 5) and B(4, -9)?

Show SolutionHide Solution↓

Let the point P(2, -5) divide the line segment AB in the ratio k : 1.

In what ratio does the point P(2, -5) divide the join of A(-3, 5) and B(4, -9)? Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

x-coordinate = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow 2 = \Big(\frac{k(4) + 1(-3)}{k + 1}\Big) \\[1em] \Rightarrow 2(k + 1) = 4k - 3 \\[1em] \Rightarrow 2k + 2 = 4k - 3 \\[1em] \Rightarrow 2 + 3 = 4k - 2k \\[1em] \Rightarrow 5 = 2k \\[1em] \Rightarrow k = \frac{5}{2} \\[1em] \Rightarrow k : 1 = \frac{5}{2} : 1 = 5 : 2.\end{aligned}$$

Hence, point P divide AB in the ratio 5 : 2.

12Exercise 13

In what ratio does the point P(a, -1) divide the join of A(1, -3) and B(6, 2)? Hence, find the value of a.

Show SolutionHide Solution↓

Let the point P(2, -5) divide the segment AB in the ratio k : 1.

In what ratio does the point P(a, -1) divide the join of A(1, -3) and B(6, 2)? Hence, find the value of a. Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

y = $\Big(\frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow -1 = \Big(\frac{k(2) + 1(-3)}{k + 1}\Big) \\[1em] \Rightarrow -1(k + 1) = 2k - 3 \\[1em] \Rightarrow -k - 1 = 2k - 3 \\[1em] \Rightarrow -1 + 3 = 2k + k \\[1em] \Rightarrow 3k = 2 \\[1em] \Rightarrow k = \frac{2}{3} \\[1em] \Rightarrow k : 1 = \frac{2}{3} : 1 = 2 : 3.\end{aligned}$$

By section-formula,

x-coordinate = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substitute values we get:

$$\begin{aligned}\Rightarrow a = \Big(\frac{2 \times 6 + 3 \times 1}{2 + 3}\Big) \\[1em] = \Big(\frac{12 + 3}{5}\Big) \\[1em] = \frac{15}{5} \\[1em] = 3.\end{aligned}$$

Hence, point P divide AB in the ratio 2 : 3 and value of a = 3.

13Exercise 13

The line segment joining A(2, 3) and B(6, -5) is intercepted by the x-axis at the point k. Find the ratio in which k divides AB. Also, write the co-ordinates of the point k.

Show SolutionHide Solution↓

Since the point k lies on the x-axis, its y-coordinate must be 0. Let the coordinates of k be (x, 0).

Let k divide the line segment joining A(2, 3) and B(6, -5) in the ratio m1:m2

The line segment joining A(2, 3) and B(6, -5) is intercepted by the x-axis at the point k. Find the ratio in which k divides AB. Also, write the co-ordinates of the point k. Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

y = $\Big(\frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{m_1(-5) + m_2(3)}{m_1 + m_2}\Big) \\[1em] \Rightarrow -5m_1 + 3m_2 = 0 \\[1em] \Rightarrow 5m_1 = 3m_2 \\[1em] \Rightarrow \frac{m_1}{m_2} = \frac{3}{5} \\[1em] \Rightarrow m_1 : m_2 = 3 : 5.\end{aligned}$$

By section-formula,

x = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow x = \Big(\frac{3(6) + 5(2)}{3 + 5}\Big) \\[1em] \Rightarrow x = \Big(\frac{18 + 10}{8}\Big) \\[1em] \Rightarrow x = \Big(\frac{28}{8}\Big) \\[1em] \Rightarrow x = \frac{7}{2}\end{aligned}$$

Hence, ratio in which k divides AB = 3 : 5 and coordinates of the point k are $\Big(\frac{7}{2}, 0\Big)$ .

14Exercise 13

In what ratio is the segment joining the points A(6, 5) and B(-3, 2) divided by the y-axis? Find the point at which the y-axis cuts AB.

Show SolutionHide Solution↓

When a point lies on the y-axis, its x-coordinate is always 0. Let the point where the y-axis cuts AB be P(0, y).

Let ratio in which P divides AB be m1 : m2.

In what ratio is the segment joining the points A(6, 5) and B(-3, 2) divided by the y-axis? Find the point at which the y-axis cuts AB. Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

x = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{m_1(-3) + m_2(6)}{m_1 + m_2}\Big) \\[1em] \Rightarrow 0 = -3m_1 + 6m_2 \\[1em] \Rightarrow 3m_1 = 6m_2 \\[1em] \Rightarrow \frac{m_1}{m_2} = \frac{6}{3} = 2.\end{aligned}$$

Thus, m1 : m2 = 2 : 1.

By section-formula,

y = $\Big(\frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substitute values we get:

$$\begin{aligned}\Rightarrow y = \Big(\frac{2(2) + 1(5)}{2 + 1}\Big) \\[1em] = \Big(\frac{4 + 5}{3}\Big) \\[1em] = \Big(\frac{9}{3}\Big) \\[1em] = 3.\end{aligned}$$

P = (0, y) = (0, 3).

Hence, AB is divided in ratio 2 : 1 and point at which the y-axis cuts AB is (0, 3).

15Exercise 13

(i) Write down the co-ordinates of the point P that divides the line segment joining A(-4, 1) and B(17, 10) in the ratio 1 : 2.

(ii) Calculate the distance OP, where O is the origin.

(iii) In what ratio does the y-axis divide the line AB?

Show SolutionHide Solution↓

(i) The point P divides the line segment joining A(-4, 1) and B(17, 10) in the ratio m1 : m2 = 1 : 2.

Let coordinates of P be (x, y).

Draw co-ordinate axes and represent the following points : Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{1(17) + 2(-4)}{1 + 2}, \frac{1(10) + 2(1)}{1 + 2}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{17 - 8}{3}, \frac{10 + 2}{3}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{9}{3}, \frac{12}{3}\Big) \\[1em] \Rightarrow (x, y) = (3, 4).\end{aligned}$$

P = (x, y) = (3, 4)

Hence, coordinates of P = (3, 4).

(ii) Using distance formula,

d = $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$

Substitute values we get,

$$\begin{aligned}OP = \sqrt{(3 - 0)^2 + (4 - 0)^2} \\[1em] = \sqrt{(3)^2 + (4)^2} \\[1em] = \sqrt{9 + 16} \\[1em] = \sqrt{25} \\[1em] = \text{5 units}.\end{aligned}$$

Hence, distance of OP is 5 units.

(iii) A point on the y-axis has an x-coordinate of 0. Let the y-axis cut AB at K(0, y). let the ratio be k : 1.

By section-formula,

x = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substitute values we get,

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{k(17) + 1(-4)}{k + 1}\Big) \\[1em] \Rightarrow 17k - 4 = 0 \\[1em] \Rightarrow 17k = 4 \\[1em] \Rightarrow k = \frac{4}{17} \\[1em] \Rightarrow k : 1 = \frac{4}{17} : 1 = 4 : 17.\end{aligned}$$

Hence, y-axis cut line AB in ratio 4 : 17.

16Exercise 13

The line segment joining P(-4, 5) and Q(3, 2) intersects the y-axis at R. PM and QN are perpendiculars from P and Q on the x-axis. Find :

The line segment joining P(-4, 5) and Q(3, 2) intersects the y-axis at R. PM and QN are perpendiculars from P and Q on the x-axis. Find : Reflection, RSA Mathematics Solutions ICSE Class 10.

(i) the ratio PR : RQ

(ii) the coordinates of R.

(iii) the area of quadrilateral PMNQ.

Show SolutionHide Solution↓

(i) The point R lies on the y-axis, so its x-coordinate is 0.

The line segment joining P(-4, 5) and Q(3, 2) intersects the y-axis at R. PM and QN are perpendiculars from P and Q on the x-axis. Find : Reflection, RSA Mathematics Solutions ICSE Class 10.

Let R(0, y) divide the line segment PQ in the ratio m1 : m2

By section-formula,

x = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substitute values we get,

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{m_1(3) + m_2(-4)}{m_1 + m_2}\Big) \\[1em] \Rightarrow 0 = 3m_1 - 4m_2 \\[1em] \Rightarrow 3m_1 = 4m_2 \\[1em] \Rightarrow \frac{m_1}{m_2} = \frac{4}{3}.\end{aligned}$$

Hence, the ratio PR : RQ = 4 : 3.

(ii) Given,

P(-4, 5) and Q(3, 2)

m1 : m2 = 4 : 3.

By section-formula,

y = $\Big(\frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substitute values we get,

$$\begin{aligned}\Rightarrow y = \Big(\frac{4(2) + 3(5)}{4 + 3}\Big) \\[1em] \Rightarrow y = \Big(\frac{8 + 15}{7}\Big) \\[1em] \Rightarrow y = \Big(\frac{23}{7}\Big).\end{aligned}$$

Hence, the coordinates of R = $\Big(0, \frac{23}{7}\Big)$.

(iii) From figure,

PQNM is a trapezium, with PM and QN being the parallel sides, as both are perpendicular to x-axis.

From figure,

PM = 5 units, MN = 7 units and QN = 2 units.

The area of a trapezoid is given by :

Area = $\frac{1}{2}$ × Sum of parallel sides × Distance between them

$$\begin{aligned}= \frac{1}{2} \times (PM + QN) \times MN \\[1em] = \frac{1}{2} \times (5 + 2) \times 7 \\[1em] = \frac{49}{2} \\[1em] = 24.5 \text{ sq. units}\end{aligned}$$

Hence, area of PQNM = 24.5 sq.units.

17Exercise 13

In the given figure, the line segment AB meets x-axis at A and y-axis at B. The point P(-3, 1) on AB divides it in ratio 2 : 3. Find the coordinates of A and B.

In the given figure, the line segment AB meets x-axis at A and y-axis at B. The point P(-3, 1) on AB divides it in ratio 2 : 3. Find the coordinates of A and B. Reflection, RSA Mathematics Solutions ICSE Class 10.
Show SolutionHide Solution↓

Since, point A and B lies on x-axis and y-axis respectively. Let their coordinates be A(a, 0) and B(0, b).

Given,

The line segment AB be divided by point P(-3, 1) in the ratio AP : PB = 2 : 3.

By section formula,

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big) \\[1em] \Rightarrow (-3, 1) = \Big(\frac{2(0) + 3(a)}{2 + 3}, \frac{2(b) + 3(0)}{2 + 3}\Big) \\[1em] \Rightarrow (-3, 1) = \Big(\frac{3a}{5}, \frac{2b}{5}\Big) \\[1em] \Rightarrow -3 = \Big(\frac{3a}{5}\Big), 1 = \Big(\frac{2b}{5}\Big) \\[1em] \Rightarrow -15 = 3a, 5 = 2b \\[1em] \Rightarrow a = \frac{-15}{3}, b = \frac{5}{2} \\[1em] \Rightarrow a = -5, b = \frac{5}{2} \\[1em] \Rightarrow A = (a, 0) = (-5, 0) \\[1em] \Rightarrow B = (0, b) = \Big(0, \frac{5}{2}\Big).\end{aligned}$$

Hence, A(-5, 0) and $B\Big(0, \frac{5}{2}\Big)$.

18Exercise 13

Show that the line segment joining the points A(-5, 8) and B(10, -4) is trisected by the coordinate axes. Also, find the points of trisection of AB.

Show SolutionHide Solution↓

Let x-axis divide AB in the ratio k : 1 at the point P(x, 0).

Show that the line segment joining the points A(-5, 8) and B(10, -4) is trisected by the coordinate axes. Also, find the points of trisection of AB. Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

y = $\Big(\frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get,

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{k(-4) + 1(8)}{k + 1}\Big) \\[1em] \Rightarrow 0 = \Big(\frac{-4k + 8}{k + 1}\Big) \\[1em] \Rightarrow 0 = -4k + 8 \\[1em] \Rightarrow 4k = 8 \\[1em] \Rightarrow k = \frac{8}{4} = 2.\end{aligned}$$

The x-axis divides AB in the ratio k : 1 = 2 : 1.

Thus, m1 : m2 = 2 : 1.

By section-formula,

x = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substituting values we get,

$$\begin{aligned}\Rightarrow x = \Big(\frac{2(10) + 1(-5)}{2 + 1}\Big) \\[1em] \Rightarrow x = \Big(\frac{20 - 5}{3}\Big) \\[1em] \Rightarrow x = \Big(\frac{15}{3}\Big) \\[1em] \Rightarrow x = 5.\end{aligned}$$

The coordinates of P = (x, 0) = (5, 0).

Let the y-axis divide AB in the ratio p : 1 at the point Q(0, y).

By section-formula,

x = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}\Big)$

Substituting values we get,

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{p(10) + 1(-5)}{p + 1}\Big) \\[1em] \Rightarrow 0 = \Big(\frac{10p - 5}{p + 1}\Big) \\[1em] \Rightarrow 10p - 5 = 0 \\[1em] \Rightarrow 10p = 5 \\[1em] \Rightarrow p = \frac{5}{10} \\[1em] \Rightarrow p = \frac{1}{2} \\[1em] \Rightarrow p : 1 = \frac{1}{2} : 1 = 1 : 2.\end{aligned}$$

By section-formula,

y = $\Big(\frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substitute values we get,

$$\begin{aligned}\Rightarrow y = \Big(\frac{1 \times -4 + 2 \times 8}{1 + 2}\Big) \\[1em] = \Big(\frac{-4 + 16}{3}\Big) \\[1em] = \frac{12}{3} \\[1em] = 4.\end{aligned}$$

The coordinates of Q = (0, y) = (0, 4).

Hence, points of trisection of AB are Q(5, 0) and P(0, 4).

19Exercise 13

The mid-points of the sides BC, CA and AB of ΔABC are D(2, 1), E(-1, -3) and F(4, 5) respectively. Find the co-ordinates of A, B and C.

Show SolutionHide Solution↓

Let the vertices of ΔABC be A(x1, y1), B(x2, y2), and C(x3, y3).

The mid-points of the sides BC, CA and AB of ΔABC are D(2, 1), E(-1, -3) and F(4, 5) respectively. Find the co-ordinates of A, B and C. Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Given,

D(2, 1) is the midpoint of BC.

Substitute values we get,

$$\begin{aligned}\Rightarrow \frac{x_2 + x_3}{2} = 2 \\[1em] \Rightarrow x_2 + x_3 = 4 \text{ ....(1)} \\[1em] \Rightarrow \frac{y_2 + y_3}{2} = 1 \\[1em] \Rightarrow y_2 + y_3 = 2 \text{ ....(2)}\end{aligned}$$

Given,

E(-1, -3) is the midpoint of CA.

$$\begin{aligned}\Rightarrow \frac{x_3 + x_1}{2} = -1 \\[1em] \Rightarrow x_3 + x_1 = -2 \text{ .....(3)} \\[1em] \Rightarrow \frac{y_3 + y_1}{2} = -3 \\[1em] \Rightarrow y_3 + y_1 = -6 \text{ ....(4)}\end{aligned}$$

Given,

F(4, 5) is the midpoint of CA.

$$\begin{aligned}\Rightarrow \frac{x_1 + x_2}{2} = 4 \\[1em] \Rightarrow x_1 + x_2 = 8 \text{ ....(5)} \\[1em] \Rightarrow \frac{y_1 + y_2}{2} = 5 \\[1em] \Rightarrow y_1 + y_2 = 10 \text{ ....(6)}\end{aligned}$$

Adding the three equations (1), (3) and (5), we get :

⇒ (x2 + x3) + (x3 + x1) + (x1 + x2) = 4 + (-2) + 8

⇒ 2x1 +2x2 + 2x3 = 10

⇒ 2(x1 +x2 + x3) = 10

⇒ (x1 +x2 + x3) = $\frac{10}{2}$

⇒ (x1 +x2 + x3) = 5 .....(7)

Subtract (Eq. 3) from (Eq. 7) :

⇒ (x1 +x2 + x3) - ( x2 + x3) = 5 - 4

⇒ (x1 +x2 + x3 -x2 - x3) = 5 - 4

⇒ x1 = 1.

Subtract (Eq. 2) from (Eq. 7) :

⇒ (x1 +x2 + x3) - ( x3 + x1) = 5 - (-2)

⇒ (x1 +x2 + x3 -x3 - x1) = 5 + 2

⇒ x2 = 7.

Subtract (Eq. 5) from (Eq. 7):

⇒ (x1 +x2 + x3) - ( x1 + x2) = 5 - 8

⇒ (x1 +x2 + x3 -x1 - x2) = -3

⇒ x3 = -3.

Adding equations (2), (4) and (5), we get :

⇒ (y2 + y3) + (y3 + y1) + (y1 + y2) = 2 + (-6) + 10

⇒ 2y1 +2y2 + 2y3 = 6

⇒ 2(y1 +y2 + y3) = 6

⇒ (y1 +y2 + y3) = $\frac{6}{2}$

⇒ (y1 +y2 + y3) = 3 .....(8)

Subtract (Eq. 2) from (Eq. 8):

⇒ (y1 +y2 + y3) - ( y2 + y3) = 3 - 2

⇒ (y1 +y2 + y3 -y2 - y3) = 1

⇒ y1 = 1.

Subtract (Eq. 4) from (Eq. 8):

⇒ (y1 + y2 + y3) - ( y3 + y1) = 3-(-6)

⇒ (y1 +y2 + y3 -y3 - y1) = 3 + 6

⇒ y2 = 9.

Subtract (Eq. 6) from (Eq. 8):

⇒ (y1 + y2 + y3) - ( y1 + y2) = 3 - 10

⇒ (y1 +y2 + y3 -y1 - y2) = -7

⇒ y3 = -7.

⇒ A = (x1, y1) = (1, 1), B = (x2, y2) = (7, 9), C = (x3, y3) = (-3, -7).

Hence, A = (1, 1), B = (7, 9) and C = (-3, -7).

20Exercise 13

Prove that the points A(-2, -1), B(1, 0), C(4, 3) and D(1, 2) are the vertices of a parallelogram ABCD.

Show SolutionHide Solution↓

Given,

A(-2, -1), B(1, 0), C(4, 3) and D(1, 2).

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

The Midpoint of Diagonal AC :

$$\begin{aligned}\Rightarrow M_{(AC)} = \Big(\frac{-2 + 4}{2}, \frac{-1 + 3}{2}\Big) \\[1em] \Rightarrow M_{(AC)} = \Big(\frac{2}{2}, \frac{2}{2}\Big) \\[1em] \Rightarrow M_{(AC)} = (1, 1).\end{aligned}$$

The Midpoint of Diagonal BD :

$$\begin{aligned}\Rightarrow M_{(BD)} = \Big(\frac{1 + 1}{2}, \frac{0 + 2}{2}\Big) \\[1em] \Rightarrow M_{(BD)} = \Big(\frac{2}{2}, \frac{2}{2}\Big) \\[1em] \Rightarrow M_{(BD)} = (1, 1)\end{aligned}$$

Since the midpoint of diagonal AC, MAC(1, 1), is the same as the midpoint of diagonal BD, MBD (1, 1), the diagonals AC and BD bisect each other.

We know that,

A quadrilateral is a parallelogram if its diagonals bisect each other.

Hence, proved that ABCD is a parallelogram.

21Exercise 13

If the points A(-2, -1), B(1, 0), C(a, 3) and D(1, b) form a parallelogram, find the values of a and b.

Show SolutionHide Solution↓

We know that,

Diagonals of a parallelogram bisect each other.

Since, ABCD is a // gm.

Thus, Mid-point of AC = Mid-point of BD.

Given,

A(-2, -1), B(1, 0), C(a, 3) and D(1, b)

If the points A(-2, -1), B(1, 0), C(a, 3) and D(1, b) form a parallelogram, find the values of a and b. Reflection, RSA Mathematics Solutions ICSE Class 10.

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Mid-point of AC :

$$\begin{aligned}\Rightarrow M_{AC} = \Big(\frac{-2 + a}{2}, \frac{-1 + 3}{2}\Big) \\[1em] \Rightarrow M_{AC} = \Big(\frac{-2 + a}{2}, \frac{2}{2}\Big) \\[1em] \Rightarrow M_{AC} = \Big(\frac{-2 + a}{2}, 1\Big).\end{aligned}$$

Midpoint of Diagonal BD :

$$\begin{aligned}\Rightarrow M_{BD} = \Big(\frac{1 + 1}{2}, \frac{0 + b}{2}\Big) \\[1em] \Rightarrow M_{BD} = \Big(\frac{2}{2}, \frac{b}{2}\Big) \\[1em] \Rightarrow M_{BD} = \Big(1, \frac{b}{2}\Big) .\end{aligned}$$

Equating the x-coordinates of mid-points of AC and BD, we get :

⇒ $\frac{-2 + a}{2}$ = 1

⇒ -2 + a = 2

⇒ a = 2 + 2

⇒ a = 4.

Equating the y-coordinates:

⇒ 1 = $\frac{b}{2}$

⇒ b = 2.

Hence, a = 4 and b = 2.

22Exercise 13

The three vertices of a parallelogram ABCD, taken in order, are A(-1, 0), B(3, 1) and C(2, 2). Find the co-ordinates of the fourth vertex of the parallelogram.

Show SolutionHide Solution↓

Let coordinates of D be (x, y).

The three vertices of a parallelogram ABCD, taken in order, are A(-1, 0), B(3, 1) and C(2, 2). Find the co-ordinates of the fourth vertex of the parallelogram. Reflection, RSA Mathematics Solutions ICSE Class 10.

By using mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Mid-point of AC :

$$\begin{aligned}\Rightarrow M_{AC} = \Big(\frac{-1 + 2}{2}, \frac{0 + 2}{2}\Big) \\[1em] \Rightarrow M_{AC} = \Big(\frac{1}{2}, 1\Big).\end{aligned}$$

Midpoint of Diagonal BD :

$\Rightarrow M_{BD} = \Big(\frac{3 + x}{2}, \frac{1 + y}{2}\Big)$

Since its a parallelogram, the midpoint of diagonal AC must be equal to the midpoint of diagonal BD, as diagonals bisect each other.

Equating the x-coordinates:

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

⇒ 3 + x = 1

⇒ x = 1 - 3

⇒ x = -2.

Equating the y-coordinates:

$\Rightarrow \frac{1 + y}{2} = 1$

⇒ 1 + y = 2

⇒ y = 2 - 1

⇒ y = 1.

Hence, coordinates of D = (-2, 1).

23Exercise 13

Find the lengths of the medians of a ΔABC whose vertices are A(-1, 3), B(1, -1) and C(5, 1). Also, find the co-ordinates of the centroid of ΔABC.

Show SolutionHide Solution↓

Using the Midpoint Formula,

$(x, y) = \Big( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \Big)$.

Let D be the midpoint of BC.

Find the lengths of the medians of a ΔABC whose vertices are A(-1, 3), B(1, -1) and C(5, 1). Also, find the co-ordinates of the centroid of ΔABC. Reflection, RSA Mathematics Solutions ICSE Class 10.

$$\begin{aligned}\Rightarrow D = \Big( \frac{1 + 5}{2}, \frac{-1 + 1}{2} \Big) \\[1em] \Rightarrow D = \Big( \frac{6}{2}, \frac{0}{2} \Big) \\[1em] \Rightarrow D = (3, 0).\end{aligned}$$

Let E be the midpoint of AC.

$$\begin{aligned}\Rightarrow E = \Big( \frac{-1 + 5}{2}, \frac{3 + 1}{2} \Big) \\[1em] \Rightarrow E = \Big( \frac{4}{2}, \frac{4}{2} \Big) \\[1em] \Rightarrow E = (2, 2).\end{aligned}$$

Let F be the midpoint of AB.

$$\begin{aligned}\Rightarrow F = \Big( \frac{-1 + 1}{2}, \frac{3 + (-1)}{2} \Big) \\[1em] \Rightarrow F = \Big( \frac{0}{2}, \frac{2}{2} \Big) \\[1em] \Rightarrow F = (0, 1).\end{aligned}$$

Length of Median AD : A(-1, 3) and D(3, 0)

Using Distance Formula,

$D = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$.

Substituting values we get:

$$\begin{aligned}AD = \sqrt{(3 - (-1))^2 + (0 - 3)^2} \\[1em] = \sqrt{(4)^2 + (-3)^2} \\[1em] = \sqrt{16 + 9} \\[1em] = \sqrt{25} \\[1em] = 5 \text{ units}.\end{aligned}$$

Length of Median BE:

B(1, -1) and E(2, 2)

$$\begin{aligned}BE = \sqrt{(2 - 1)^2 + (2 - (-1))^2} \\[1em]= \sqrt{(1)^2 + (3)^2} \\[1em] = \sqrt{1 + 9} \\[1em] = \sqrt{10} \text{ units}.\end{aligned}$$

Length of Median CF:

C(5, 1) and F(0, 1)

$$\begin{aligned}CF = \sqrt{(0 - 5)^2 + (1 - 1)^2} \\[1em] = \sqrt{(-5)^2 + (0)^2} \\[1em] = \sqrt{25 + 0} \\[1em] = \sqrt{25} \\[1em] = 5 \text{ units}.\end{aligned}$$

Centroid of triangle (G) $= \Big( \frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3} \Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow \text{Centroid} = \Big(\frac{-1 + 1 + 5}{3}, \frac{3 + (-1) + 1}{3}\Big) \\[1em] = \Big(\frac{5}{3}, \frac{3}{3}\Big) \\[1em] = \Big(\frac{5}{3}, 1\Big).\end{aligned}$$

Hence, AD = 5 units , $BE = \sqrt{10}$ units, CF = 5 units, coordinates of centroid are $\Big(\frac{5}{3}, 1\Big)$.

24Exercise 13

Find the co-ordinates of the centroid of ΔPQR whose vertices are P(6, 3), Q(-2, 5) and R(-1, 7).

Show SolutionHide Solution↓

By using the centroid formula,

$(x, y) = \Big( \frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3} \Big)$

P(6, 3), Q(-2, 5) and R(-1, 7)

Find the co-ordinates of the centroid of ΔPQR whose vertices are P(6, 3), Q(-2, 5) and R(-1, 7). Reflection, RSA Mathematics Solutions ICSE Class 10.

Substitute values we get:

$$\begin{aligned}\Rightarrow (x, y) = \Big( \frac{6 + (-2) + (-1)}{3}, \frac{3 + 5 + 7}{3} \Big) \\[1em] \Rightarrow (x, y) = \Big( \frac{6 - 3}{3}, \frac{15}{3} \Big) \\[1em] \Rightarrow (x, y) = \Big( \frac{3}{3}, \frac{15}{3} \Big) \\[1em] \Rightarrow (x, y) = (1, 5).\end{aligned}$$

Hence, coordinates of centroid of ΔPQR = (1, 5).

25Exercise 13

Find the co-ordinates of the point of intersection of the medians of the triangle whose vertices are A(-7, 5), B(-1, -3) and C(5, 7).

Show SolutionHide Solution↓

The medians of a triangle intersect at centroid of triangle.

By using the centroid formula,

$(x, y) = \Big(\frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3} \Big)$

A(-7, 5), B(-1, -3) and C(5, 7)

Find the co-ordinates of the point of intersection of the medians of the triangle whose vertices are A(-7, 5), B(-1, -3) and C(5, 7). Reflection, RSA Mathematics Solutions ICSE Class 10.

Substitute values we get:

$$\begin{aligned}\Rightarrow (x, y) = \Big( \frac{-7 + (-1) + 5}{3}, \frac{5 + (-3) + 7}{3} \Big) \\[1em] \Rightarrow (x, y) = \Big( \frac{-8 + 5}{3}, \frac{5 + 4}{3} \Big) \\[1em] \Rightarrow (x, y) = \Big( \frac{-3}{3}, \frac{9}{3} \Big) \\[1em] \Rightarrow (x, y) = (-1, 3).\end{aligned}$$

Hence, co-ordinates of the point of intersection of the medians = (-1, 3).

26Exercise 13

If G(-2, 1) is the centroid of ΔABC, two of whose vertices are A(1, -6) and B(-5, 2), find the third vertex of the triangle.

Show SolutionHide Solution↓

Let coordinates of third vertex be C(x3, y3).

By using the centroid formula,

$(x, y) = \Big( \frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3} \Big)$

Given,

G(-2, 1) is the centroid.

If G(-2, 1) is the centroid of ΔABC, two of whose vertices are A(1, -6) and B(-5, 2), find the third vertex of the triangle. Reflection, RSA Mathematics Solutions ICSE Class 10.

Substituting values we get :

$$\begin{aligned}\Rightarrow (-2, 1) = \Big( \frac{1 + (-5) + x_3}{3}, \frac{-6 + 2 + y_3}{3}\Big) \\[1em] \Rightarrow -2 = \Big( \frac{1 + (-5) + x_3}{3}\Big), 1 = \Big( \frac{-6 + 2 + y_3}{3}\Big) \\[1em] \Rightarrow -6 = 1 + (-5) + x_3, 3 = -6 + 2 + y_3 \\[1em] \Rightarrow -6 = -4 + x_3, 3 = -4 + y_3 \\[1em] \Rightarrow -6 + 4 = x_3, 3 + 4 = y_3 \\[1em] \Rightarrow x_3 = -2, y_3 = 7.\end{aligned}$$

Hence, coordinates of third vertex = (-2, 7).

27Exercise 13

A(6, y), B(-4, 4) and C(x, -1) are the vertices of ΔABC whose centroid is the origin. Calculate the values of x and y.

Show SolutionHide Solution↓

By using the centroid formula,

$(x, y) = \Big( \frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3} \Big)$

Origin (0,0) is the centroid of triangle ABC.

A(6, y), B(-4, 4) and C(x, -1) are the vertices of ΔABC whose centroid is the origin. Calculate the values of x and y. Reflection, RSA Mathematics Solutions ICSE Class 10.

Solving for x-coordinate:

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{6 + (-4) + x}{3}\Big) \\[1em] \Rightarrow 0 = 2 + x \\[1em] \Rightarrow x = -2.\end{aligned}$$

Solving for y-coordinate:

$$\begin{aligned}\Rightarrow 0 = \Big(\frac{y + 4 + (-1)}{3}\Big) \\[1em] \Rightarrow 0 = y + 3 \\[1em] \Rightarrow y = -3.\end{aligned}$$

Hence, x = -2 and y = -3.

28Exercise 13

ABC is a triangle and G(4, 3) is its centroid. If A(1, 3), B(4, b) and C(a, 1) be the vertices, find the values of a and b and hence find the length of side BC.

Show SolutionHide Solution↓

By using the centroid formula,

$(x, y) = \Big(\frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3}\Big)$

Given,

A(1, 3), B(4, b) and C(a, 1).

G(4, 3) is the centroid of triangle ABC.

ABC is a triangle and G(4, 3) is its centroid. If A(1, 3), B(4, b) and C(a, 1) be the vertices, find the values of a and b and hence find the length of side BC. Reflection, RSA Mathematics Solutions ICSE Class 10.

Solving for x-coordinate :

$$\begin{aligned}\Rightarrow 4 = \frac{1 + 4 + a}{3} \\[1em] \Rightarrow 12 = 5 + a \\[1em] \Rightarrow a = 12 - 5 \\[1em] \Rightarrow a = 7.\end{aligned}$$

C = (a, 1) = (7, 1)

Solving for y-coordinate :

$$\begin{aligned}\Rightarrow 3 = \frac{3 + b + 1}{3} \\[1em] \Rightarrow 9 = 4 + b \\[1em] \Rightarrow b = 9 - 4 \\[1em] \Rightarrow b = 5.\end{aligned}$$

B = (4, b) = (4, 5)

By using distance formula,

$D = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$.

Substituting values we get:

$$\begin{aligned}BC = \sqrt{(7 - 4)^2 + (1 - 5)^2} \\[1em] = \sqrt{(3)^2 + (-4)^2} \\[1em] = \sqrt{9 + 16} \\[1em] = \sqrt{25} \\[1em] = 5 \text{ units}.\end{aligned}$$

Hence, a = 7 and b = 5, length of BC = 5 units.

29Exercise 13

Calculate the ratio in which the line segment joining A(-4, 2) and B(3, 6) is divided by the point P(x, 3). Also, find

(i) x

(ii) length of AP.

Show SolutionHide Solution↓

(i) Let the point P(x, 3) divide the line segment joining A(-4, 2) and B(3, 6) in the ratio m1 : m2.

Calculate the ratio in which the line segment joining A(-4, 2) and B(3, 6) is divided by the point P(x, 3). Also, find Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow 3 = \Big(\frac{m_1(6) + m_2(2)}{m_1 + m_2}\Big) \\[1em] \Rightarrow 3(m_1 + m_2) = {6m_1 + 2m_2} \\[1em] \Rightarrow 3m_1 + 3m_2 = 6m_1 + 2m_2 \\[1em] \Rightarrow 3m_2 - 2m_2 = 6m_1 - 3m_1 \\[1em] \Rightarrow m_2 = 3m_1 \\[1em] \Rightarrow \frac{m_1}{m_2} = \frac{1}{3}.\end{aligned}$$

Solving for x-coordinate with the ratio $m_1 = 1$ and $m_2 = 3$:

$$\begin{aligned}\Rightarrow x = \frac{(1)(3) + (3)(-4)}{1 + 3} \\[1em] = \frac{3 - 12}{4} \\[1em] = \frac{-9}{4}.\end{aligned}$$

Hence, x = $\frac{-9}{4}$.

(ii) Solving length of AP

By using Distance Formula

$D = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$

A(-4, 2) and $P\Big(\frac{-9}{4}, 3\Big)$.

$$\begin{aligned}AP = \sqrt{\Big(-\frac{9}{4} - (-4)\Big)^2 + (3 - 2)^2} \\[1em] =\sqrt{\Big(-\frac{9}{4} + \frac{16}{4}\Big)^2 + (1)^2} \\[1em] = \sqrt{\Big(\frac{7}{4}\Big)^2 + 1^2} \\[1em] = \sqrt{\frac{49}{16} + \frac{16}{16}} \\[1em] = \sqrt{\frac{65}{16}} \\[1em] = \frac{\sqrt{65}}{4} \text{ units}\end{aligned}$$

Hence, length of AP = $\frac{\sqrt{65}}{4}$ units.

30Exercise 13

In what ratio is the line joining P(5, 3) and Q(-5, 3) divided by the x-axis? Also, find the co-ordinates of the point of intersection.

Show SolutionHide Solution↓

Let point on x-axis dividing PQ be (a, 0).

By section formula,

y = $\frac{m_1y_2 + m_2y_1}{m_1 + m_2}$

Substituting values we get :

$$\begin{aligned}\Rightarrow 0 = \frac{m_1 \times 3 + m_2 \times 3}{m_1 + m_2} \\[1em] \Rightarrow 0 = 3m_1 + 3m_2 \\[1em] \Rightarrow 3m_1 = -3m_2 \\[1em] \Rightarrow \frac{m_1}{m_2} = -\frac{3}{3} \\[1em] \Rightarrow \frac{m_1}{m_2} = -\frac{1}{1}\end{aligned}$$

The negative ratio shows that the line PQ does not intersects with x-axis.

Hence, the x-axis does not intersect the line PQ, so no ratio or point of intersection exists.

31Exercise 13

Find a point P which divides internally the line segment joining the points A(-3, 9) and B(1, -3) in the ratio 1 : 3.

Show SolutionHide Solution↓

Let Point P divides the line segment joining A(−3, 9) and B(1, −3) internally in the ratio m1 : m2 = 1 : 3.

Find a point P which divides internally the line segment joining the points A(-3, 9) and B(1, -3) in the ratio 1 : 3. Reflection, RSA Mathematics Solutions ICSE Class 10.

By using section formula,

P(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get:

$$\begin{aligned}P = \Big(\frac{1 \times 1 + 3 \times -3}{1 + 3}, \frac{1 \times -3 + 3 \times 9}{1 + 3}\Big) \\[1em] = \Big(\frac{1 - 9}{4}, \frac{-3 + 27}{4}\Big) \\[1em] = \Big(\frac{-8}{4}, \frac{24}{4}\Big) \\[1em] = (-2, 6).\end{aligned}$$

Hence, coordinates of P = (-2, 6).

11 Mark · Multiple Choice Questions

The coordinates of the point P which divides the join of A(5, -2) and B(9, 6) in the ratio 3 : 1 are :

Show SolutionHide Solution↓

Let point P be (x, y).

The coordinates of the point P which divides the join of A(5, -2) and B(9, 6) in the ratio 3 : 1 are : Reflection, RSA Mathematics Solutions ICSE Class 10.

Given,

m1 : m2 = 3 : 1

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{3 \times 9 + 1 \times 5}{3 + 1}, \frac{3 \times 6 + 1 \times -2}{3 + 1}\Big) \\[1em] = \Big(\frac{27 + 5}{4}, \frac{18 - 2}{4}\Big) \\[1em] = \Big(\frac{32}{4}, \frac{16}{4}\Big) \\[1em] = (8, 4).\end{aligned}$$

Hence, Option 3 is the correct option.

21 Mark · Multiple Choice Questions

The coordinates of the point on x-axis which divides the line segment joining the points (2, 3) and (5, -6) in the ratio 1 : 2 are :

Show SolutionHide Solution↓

Let point P be (x, y).

The coordinates of the point on x-axis which divides the line segment joining the points (2, 3) and (5, -6) in the ratio 1 : 2 are : Reflection, RSA Mathematics Solutions ICSE Class 10.

Given,

m1 : m2 = 1 : 2

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{1 \times 5 + 2 \times 2}{1 + 2}, \frac{1 \times (-6) + 2 \times 3}{1 + 2}\Big) \\[1em] = \Big(\frac{5 + 4}{3}, \frac{-6 + 6}{3}\Big) \\[1em] = \Big(\frac{9}{3}, \frac{0}{3}\Big) \\[1em] = (3, 0).\end{aligned}$$

Hence, Option 3 is the correct option.

31 Mark · Multiple Choice Questions

The point which divides the line segment joining the points A(3, -2) and B(6, 7) internally in the ratio 3 : 2 lies in which of the following quadrants?

Show SolutionHide Solution↓

Let point P be (x, y).

The point which divides the line segment joining the points A(3, -2) and B(6, 7) internally in the ratio 3 : 2 lies in which of the following quadrants? Reflection, RSA Mathematics Solutions ICSE Class 10.

Given,

m1 : m2 = 3 : 2

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{3 \times 6 + 2 \times 3}{3 + 2}, \frac{3 \times 7 + 2 \times (-2)}{3 + 2}\Big) \\[1em] = \Big(\frac{18 + 6}{5}, \frac{21 - 4}{5}\Big) \\[1em] = \Big(\frac{24}{5}, \frac{17}{5}\Big).\end{aligned}$$

Here, both x and y are positive.

Therefore, the point lies in the 1st Quadrant.

Hence, Option 1 is the correct option.

41 Mark · Multiple Choice Questions

If the point R(k, 4) divides the line segment joining the points P(2, 6) and Q(5, 1) in the ratio 2 : 3, then the value of k is:

Show SolutionHide Solution↓

Given,

R = (k, 4)

m1 : m2 = 2 : 3

R(k, 4) divides the line segment joining the points P(2, 6) and Q(5, 1) in the ratio 2 : 3.

If the point R(k, 4) divides the line segment joining the points P(2, 6) and Q(5, 1) in the ratio 2 : 3, then the value of k is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (k, 4) = \Big(\frac{2 \times 5 + 3 \times 2}{2 + 3}, \frac{2 \times 1 + 3 \times 6}{2 + 3}\Big) \\[1em] \Rightarrow (k, 4) = \Big(\frac{10 + 6}{5}, \frac{2 + 18}{5}\Big) \\[1em] \Rightarrow (k, 4) = \Big(\frac{16}{5}, \frac{20}{5}\Big) \\[1em] \Rightarrow (k, 4) = \Big(\frac{16}{5}, 4\Big).\end{aligned}$$

Thus, k = $\frac{16}{5}$.

Hence, Option 4 is the correct option.

51 Mark · Multiple Choice Questions

Points A(x, y), B(3, -2) and C(4, -5) are collinear. The value of y in terms of x is ∶

Show SolutionHide Solution↓

Since, points A, B and C are collinear.

∴ Slope of AB = Slope of BC.

$$\begin{aligned}\Rightarrow \frac{-2 - y}{3 - x} = \frac{-5 - (-2)}{4 - 3} \\[1em] \Rightarrow \frac{-2 - y}{3 - x} = \frac{-5 + 2}{1} \\[1em] \Rightarrow \frac{-2 - y}{3 - x} = -3 \\[1em] \Rightarrow -2 - y = -3(3 - x) \\[1em] \Rightarrow -2 - y = -9 + 3x \\[1em] \Rightarrow y = -2 + 9 - 3x \\[1em] \Rightarrow y = 7 - 3x.\end{aligned}$$

Hence, Option 4 is the correct option.

61 Mark · Multiple Choice Questions

If the point P(6, 2) divides the line segment joining A(6, 5) and B(4, y) in the ratio 3 : 1, then the value of y is :

Show SolutionHide Solution↓

Let point P be (6, 2).

If the point P(6, 2) divides the line segment joining A(6, 5) and B(4, y) in the ratio 3 : 1, then the value of y is : Reflection, RSA Mathematics Solutions ICSE Class 10.

Given,

m1 : m2 = 3 : 1

P(6, 2) divides the line segment joining A(6, 5) and B(4, y) in the ratio 3 : 1.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

We use the y–coordinate to find y.

$$\begin{aligned}\Rightarrow 2 = \frac{3 \times y + 1 \times 5}{3 + 1} \\[1em] \Rightarrow 2 = \frac{3y + 5}{4} \\[1em] \Rightarrow 8 = 3y + 5 \\[1em] \Rightarrow 3y = 3 \\[1em] \Rightarrow y = 1.\end{aligned}$$

Hence, Option 1 is the correct option.

71 Mark · Multiple Choice Questions

The ratio in which the point P(1, 2) divides the join of the points A(-2, 1) and B(7, 4) is:

Show SolutionHide Solution↓

Let the ratio in which P divides AB be k : 1.

The ratio in which the point P(1, 2) divides the join of the points A(-2, 1) and B(7, 4) is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Using the y–coordinate to find ratio.

$$\begin{aligned}\Rightarrow 2 = \Big(\frac{k(4) + 1(1)}{k + 1}\Big) \\[1em] \Rightarrow 2 = \Big(\frac{4k + 1}{k + 1}\Big) \\[1em] \Rightarrow 2(k + 1) = 4k + 1 \\[1em] \Rightarrow 2k + 2 = 4k + 1 \\[1em] \Rightarrow 2 - 1 = 4k - 2k \\[1em] \Rightarrow 2k = 1 \\[1em] \Rightarrow k = \frac{1}{2}\\[1em] \Rightarrow k : 1 = \frac{1}{2} : 1 = 1 : 2.\end{aligned}$$

Hence, Option 1 is the correct option.

81 Mark · Multiple Choice Questions

The line segment joining A(-7, 2) and B(3, -8) is divided by the x-axis in the ratio:

Show SolutionHide Solution↓

Given,

AB is divided by the x-axis, thus y-coordinate = 0 at point of division.

A(-7, 2) and B(3, -8)

Let ratio be m : n.

By section-formula,

y = $\frac{my_2 + ny_1}{m + n}$

Substituting values we get :

⇒ 0 = $\frac{m \times (-8) + n \times (2)}{m + n}$

⇒ 0 = -8m + 2n

⇒ 8m = 2n

⇒ $\frac{m}{n} = \frac{2}{8}$

⇒ $\frac{m}{n} = \frac{1}{4}$

⇒ m : n = 1 : 4.

Hence, option 1 is the correct option.

91 Mark · Multiple Choice Questions

In what ratio is the line segment joining the points P(-4, 2) and Q(8, 3) divided by y-axis?

Show SolutionHide Solution↓

Let the point where y-axis divides the line segment be R(0, y).

Let the ratio be m1 : m2.

In what ratio is the line segment joining the points P(-4, 2) and Q(8, 3) divided by y-axis? Reflection, RSA Mathematics Solutions ICSE Class 10.

Using section-formula,

$$\begin{aligned}\Rightarrow x = \frac{m_1x_2 + m_2x_1}{m_1 + m_2} \\[1em] \Rightarrow 0 = \frac{m_1 \times 8 + m_2 \times (-4)}{m_1 + m_2} \\[1em] \Rightarrow 0 = 8m_1 - 4m_2 \\[1em] \Rightarrow 8m_1 = 4m_2 \\[1em] \Rightarrow \frac{m_1}{m_2} = \frac{4}{8} = \frac{1}{2}.\end{aligned}$$

Thus, the required ratio is 1 : 2.

Hence, Option 3 is the correct option.

101 Mark · Multiple Choice Questions

Point P divides the line segment joining R(-1, 3) and S(9, 8) in the ratio k : 1. If P lies on the line x - y + 2 = 0, then the value of k is:

Show SolutionHide Solution↓

Let point P be (x, y).

Point P divides the line segment joining R(-1, 3) and S(9, 8) in the ratio k : 1. If P lies on the line x - y + 2 = 0, then the value of k is: Reflection, RSA Mathematics Solutions ICSE Class 10.

Given,

m1 : m2 = k : 1

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{k \times 9 + 1 \times (-1)}{k + 1}, \frac{k \times 8 + 1 \times 3}{k + 1}\Big) \\[1em] = \Big(\frac{9k - 1}{k + 1}, \frac{8k + 3}{k + 1}\Big).\end{aligned}$$

Since P lies on the line x - y + 2 = 0, substituting values of x and y:

$$\begin{aligned}\Rightarrow \frac{9k - 1}{k + 1} - \frac{8k + 3}{k + 1} + 2 = 0 \\[1em] \Rightarrow \frac{9k - 1 - (8k + 3)}{k + 1} + 2 = 0 \\[1em] \Rightarrow \frac{9k - 1 - 8k - 3}{k + 1} + 2 = 0 \\[1em] \Rightarrow \frac{k - 4}{k + 1} + 2 = 0 \\[1em] \Rightarrow \frac{k - 4 + 2(k + 1)}{k + 1} = 0 \\[1em] \Rightarrow \frac{k - 4 + 2k + 2}{k + 1} = 0 \\[1em] \Rightarrow \frac{3k - 2}{k + 1} = 0 \\[1em] \Rightarrow 3k - 2 = 0 \\[1em] \Rightarrow 3k = 2 \\[1em] \Rightarrow k = \frac{2}{3}.\end{aligned}$$

Hence, Option 4 is the correct option.

111 Mark · Multiple Choice Questions

In the adjoining figure, P(5, -3) and Q(3, y) are the points of trisection of the line segment joining A(7, -2) and B(1, -5). Then, y equals :

In the adjoining figure, P(5, -3) and Q(3, y) are the points of trisection of the line segment joining A(7, -2) and B(1, -5). Then, y equals : Reflection, RSA Mathematics Solutions ICSE Class 10.
Show SolutionHide Solution↓

Since P and Q trisect the line segment AB, the point Q(3, y) divides A(7, -2) and B(1, -5) in the ratio 2 : 1.

Let point Q be (3, y).

Given,

m1 : m2 = 2 : 1

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (3, y) = \Big(\frac{2 \times 1 + 1 \times 7}{2 + 1}, \frac{2 \times (-5) + 1 \times (-2)}{2 + 1}\Big) \\[1em] \Rightarrow (3, y) = \Big(\frac{2 + 7}{3}, \frac{-10 - 2}{3}\Big) \\[1em] \Rightarrow (3, y) = \Big(\frac{9}{3}, \frac{-12}{3}\Big) \\[1em] \Rightarrow (3, y) = (3, -4).\end{aligned}$$

Thus, y = -4.

Hence, Option 1 is the correct option.

121 Mark · Multiple Choice Questions

If the point P(6, -3) lies on the line segment joining points A(4, 2) and B(8, 4), then:

Show SolutionHide Solution↓

Let the ratio in which P divides AB be k : 1.

Draw co-ordinate axes and represent the following points : Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

x = $\frac{m_1x_2 + m_2x_1}{m_1 + m_2}$

Substituting values we get :

$$\begin{aligned}\Rightarrow 6 = \Big(\frac{k(8) + 1(4)}{k + 1}\Big) \\[1em] \Rightarrow 6 = \Big(\frac{8k + 4}{k + 1}\Big) \\[1em] \Rightarrow 6(k + 1) = 8k + 4 \\[1em] \Rightarrow 6k + 6 = 8k + 4 \\[1em] \Rightarrow 6 - 4 = 8k - 6k \\[1em] \Rightarrow 2 = 2k \\[1em] \Rightarrow k = \frac{1}{1} = 1:1.\end{aligned}$$

This means that P is the midpoint of AB.

∴ AP = $\frac{1}{2}$ AB.

Hence, Option 4 is the correct option.

131 Mark · Multiple Choice Questions

The mid-point of the line segment joining the points (-3, 2) and (7, 6) is:

Show SolutionHide Solution↓

Let the mid-point be M(x, y).

The mid-point of the line segment joining the points (-3, 2) and (7, 6) is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow M(x, y) = \Big(\frac{-3 + 7}{2}, \frac{2 + 6}{2}\Big) \\[1em] \Rightarrow \Big(\frac{4}{2}, \frac{8}{2}\Big) \\[1em] \Rightarrow (2, 4).\end{aligned}$$

Hence, Option 3 is the correct option.

141 Mark · Multiple Choice Questions

If A(4, 2), B(6, 5) and C(1, 4) be the vertices of ΔABC and AD is a median, then the coordinates of D are:

Show SolutionHide Solution↓

Since AD is a median, D is the mid-point of BC.

Let point D be (x, y).

If A(4, 2), B(6, 5) and C(1, 4) be the vertices of ΔABC and AD is a median, then the coordinates of D are: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{6 + 1}{2}, \frac{5 + 4}{2}\Big) \\[1em] \Rightarrow \Big(\frac{7}{2}, \frac{9}{2}\Big).\end{aligned}$$

Hence, Option 3 is the correct option.

151 Mark · Multiple Choice Questions

If (3, -6) is the mid-point of the line segment joining (0, 0) and (x, y), then the point (x, y) is:

Show SolutionHide Solution↓

Given, (3, -6) is the mid-point of the line segment joining (0, 0) and (x, y).

If (3, -6) is the mid-point of the line segment joining (0, 0) and (x, y), then the point (x, y) is: Reflection, RSA Mathematics Solutions ICSE Class 10.

$$\begin{aligned}\therefore (3, -6) = \Big(\frac{0 + x}{2}, \frac{0 + y}{2}\Big) \\[1em] \Rightarrow (3, -6) = \Big(\frac{x}{2}, \frac{y}{2}\Big) \\[1em] \Rightarrow 3 = \frac{x}{2} \text{ and } -6 = \frac{y}{2} \\[1em] \Rightarrow x = 6 \text{ and } y = -12\end{aligned}$$

(x, y) = (6, -12).

Hence, Option 3 is the correct option.

161 Mark · Multiple Choice Questions

If the line segment joining the points P and Q(3, -4) is bisected at the origin, then the coordinates of P are:

Show SolutionHide Solution↓

Let the coordinates of P be (x, y).

If the line segment joining the points P and Q(3, -4) is bisected at the origin, then the coordinates of P are: Reflection, RSA Mathematics Solutions ICSE Class 10.

Given, the origin (0, 0) is the mid-point of PQ.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (0, 0) = \Big(\frac{x + 3}{2}, \frac{y + (-4)}{2}\Big) \\[1em] \Rightarrow 0 = \frac{x + 3}{2} \text{ and } 0 = \frac{y - 4}{2} \\[1em] \Rightarrow x + 3 = 0 \text{ and } y - 4 = 0 \\[1em] \Rightarrow x = -3 \text{ and } y = 4 \\[1em] \Rightarrow P = (x, y) = (-3, 4).\end{aligned}$$

Hence, Option 4 is the correct option.

171 Mark · Multiple Choice Questions

A(-3, b) and B(1, b + 4) are two points. If the coordinates of the mid-point of AB are (-1, 1), then the value of b is :

Show SolutionHide Solution↓

Given,

Mid-point of AB = (-1, 1).

A(-3, b) and B(1, b + 4) are two points. If the coordinates of the mid-point of AB are (-1, 1), then the value of b is : Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (-1, 1) = \Big(\frac{-3 + 1}{2}, \frac{b + (b + 4)}{2}\Big) \\[1em] \Rightarrow (-1, 1) = \Big(\frac{-2}{2}, \frac{2b + 4}{2}\Big) \\[1em] \Rightarrow (-1, 1) = (-1, b + 2)\end{aligned}$$

Comparing the y-coordinates, we get :

⇒ 1 = b + 2

⇒ b = -1.

Hence, Option 1 is the correct option.

181 Mark · Multiple Choice Questions

If the point R(5, 7) is the mid-point of the line segment joining the points P(3, y) and Q(x, 9), then (x + y) equals:

Show SolutionHide Solution↓

Given,

R(5, 7) is the mid-point of the line segment joining the points P(3, y) and Q(x, 9).

If the point R(5, 7) is the mid-point of the line segment joining the points P(3, y) and Q(x, 9), then (x + y) equals: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (5, 7) = \Big(\frac{3 + x}{2}, \frac{y + 9}{2}\Big) \\[1em] \Rightarrow 5 = \frac{3 + x}{2} \text{ and } 7 = \frac{y + 9}{2} \\[1em] \Rightarrow 10 = 3 + x \text{ and } 14 = y + 9 \\[1em] \Rightarrow x = 7 \text{ and } y = 5.\end{aligned}$$

x + y = 7 + 5 = 12.

Hence, Option 3 is the correct option.

191 Mark · Multiple Choice Questions

The mid-point of the line segment joining (4p, 5) and (2, 3q) is (5, 5p - 1). The values of p and q are respectively:

Show SolutionHide Solution↓

Given,

Mid-point of the line segment joining (4p, 5) and (2, 3q) is (5, 5p - 1).

The mid-point of the line segment joining (4p, 5) and (2, 3q) is (5, 5p - 1). The values of p and q are respectively: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (5, 5p - 1) = \Big(\frac{4p + 2}{2}, \frac{5 + 3q}{2}\Big) \\[1em] \Rightarrow (5, 5p - 1) = \Big(\frac{2(2p + 1)}{2}, \frac{5 + 3q}{2}\Big) \\[1em] \Rightarrow (5, 5p - 1) = \Big(2p + 1, \frac{5 + 3q}{2}\Big)\end{aligned}$$

Comparing the x coordinates, we get :

⇒ 2p + 1 = 5

⇒ 2p = 5 - 1

⇒ 2p = 4

⇒ p = $\frac{4}{2}$

⇒ p = 2.

Comparing y-coordinates we get :

$$\begin{aligned}\Rightarrow 5p - 1 = \frac{5 + 3q}{2} \\[1em] \Rightarrow 5 \times 2 - 1 = \frac{5 + 3q}{2} \\[1em] \Rightarrow 9 = \frac{5 + 3q}{2} \\[1em] \Rightarrow 18 = 5 + 3q \\[1em] \Rightarrow 3q = 18 - 5 \\[1em] \Rightarrow 3q = 13 \\[1em] \Rightarrow q = \frac{13}{3}.\end{aligned}$$

p = 2 and q = $\frac{13}{3}$.

Hence, Option 3 is the correct option.

201 Mark · Multiple Choice Questions

A line intersects the y-axis and x-axis at the points P and Q respectively. If (2, -5) is the mid-point of PQ, then the coordinates of P and Q are respectively:

Show SolutionHide Solution↓

Let P(0, a) be the point on y-axis and Q(b, 0) be the point on x-axis.

Given, (2, -5) is the mid-point of PQ.

A line intersects the y-axis and x-axis at the points P and Q respectively. If (2, -5) is the mid-point of PQ, then the coordinates of P and Q are respectively: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (2, -5) = \Big(\frac{0 + b}{2}, \frac{a + 0}{2}\Big) \\[1em] \Rightarrow (2, -5) = \Big(\frac{b}{2}, \frac{a}{2}\Big) \\[1em] \Rightarrow 2 = \frac{b}{2} \text{ and } -5 = \frac{a}{2} \\[1em] \Rightarrow b = 4 \text{ and } a = -10.\end{aligned}$$

P(0, -10) and Q(4, 0)

Hence, Option 4 is the correct option.

211 Mark · Multiple Choice Questions

If a point $R\Big(\frac{23}{5}, \frac{33}{5}\Big)$ divides the line segment PQ joining the points P(3, 5) and Q(x, y) in the ratio 2 : 3 internally, then the values of x and y respectively are :

Show SolutionHide Solution↓

Given,

Point R = $\Big(\frac{23}{5}, \frac{33}{5}\Big)$ and P(3, 5), Q(x, y).

divides the line segment PQ joining the points P(3, 5) and Q(x, y) in the ratio 2 : 3 internally, then the values of x and y respectively are :Reflection, RSA Mathematics Solutions ICSE Class 10.

Given,

m1 : m2 = 2 : 3

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow \Big(\frac{23}{5}, \frac{33}{5}\Big) = \Big(\frac{2x + 3 \times 3}{2 + 3}, \frac{2y + 3 \times 5}{2 + 3}\Big) \\[1em] \Rightarrow \frac{23}{5} = \frac{2x + 9}{5}, \frac{33}{5} = \frac{2y + 15}{5} \\[1em] \Rightarrow 23 = 2x + 9, 33 = 2y + 15 \\[1em] \Rightarrow 23 - 9 = 2x, 33 - 15 = 2y \\[1em] \Rightarrow 14 = 2x, 18 = 2y \\[1em] \Rightarrow x = \frac{14}{2}, y = \frac{18}{2} \\[1em] \Rightarrow x = 7, y = 9.\end{aligned}$$

Therefore, the values of x and y are 7 and 9 respectively.

Hence, Option 4 is the correct option.

221 Mark · Multiple Choice Questions

The coordinates of the vertices of ΔABC are respectively (-4, -2), (6, 2) and (4, 6). The centroid G of ΔABC is:

Show SolutionHide Solution↓
The coordinates of the vertices of ΔABC are respectively (-4, -2), (6, 2) and (4, 6). The centroid G of ΔABC is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By centroid formula,

G(x, y) = $\Big(\frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow G = \Big(\frac{-4 + 6 + 4}{3}, \frac{-2 + 2 + 6}{3}\Big) \\[1em] = \Big(\frac{6}{3}, \frac{6}{3}\Big) \\[1em] = (2, 2).\end{aligned}$$

Hence, Option 1 is the correct option.

231 Mark · Multiple Choice Questions

Two vertices of a ΔABC are A(-1, 4) and B(5, 2) and its centroid is (0, -3). The coordinates of C are :

Show SolutionHide Solution↓

Let the coordinates of C be (x, y).

Two vertices of a ΔABC are A(-1, 4) and B(5, 2) and its centroid is (0, -3). The coordinates of C are : Reflection, RSA Mathematics Solutions ICSE Class 10.

By centroid formula,

Centroid = $\Big(\frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3}\Big)$

Given,

G(0, -3) is the centroid of the triangle.

Substituting values we get :

$$\begin{aligned}\Rightarrow (0, -3) = \Big(\frac{-1 + 5 + x}{3}, \frac{4 + 2 + y}{3}\Big) \\[1em] \Rightarrow (0, -3) = \Big(\frac{4 + x}{3}, \frac{6 + y}{3}\Big) \\[1em] \Rightarrow 0 = \frac{4 + x}{3} \text{ and } -3 = \frac{6 + y}{3} \\[1em] \Rightarrow 4 + x = 0 \text{ and } 6 + y = -9 \\[1em] \Rightarrow x = -4 \text{ and } y = -9 - 6 \\[1em] \Rightarrow x = -4 \text{ and } y = -15.\end{aligned}$$

C = (x, y) = (-4, -15).

Hence, Option 3 is the correct option.

241 Mark · Multiple Choice Questions

In the adjoining diagram, G is the centroid of △ ABC. A(3, -3), B(2, -6), C(x, y) and G(5, -5). The coordinates of point D are :

In the adjoining diagram, G is the centroid of △ ABC. A(3, -3), B(2, -6), C(x, y) and G(5, -5). The coordinates of point D are : Maths Competency Focused Practice Questions Class 10 Solutions.
Show SolutionHide Solution↓

By formula,

Centroid of triangle = $\Big(\frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3}\Big)$

$$\begin{aligned}\therefore (5, -5) = \Big(\frac{3 + 2 + x}{3}, \frac{(-3) + (-6) + y}{3}\Big) \\[1em] \Rightarrow (5, -5) = \Big(\frac{x + 5}{3}, \frac{y - 9}{3}\Big) \\[1em] \Rightarrow \frac{x + 5}{3} = 5 \text{ and } \frac{y - 9}{3} = -5 \\[1em] \Rightarrow x + 5 = 15 \text{ and } y - 9 = -15 \\[1em] \Rightarrow x = 15 - 5 = 10 \text{ and } y = -15 + 9 = -6.\end{aligned}$$

C(x, y) = (10, -6).

Since, centroid is the point of intersection of all the three medians of a triangle.

∴ AD is the median.

∴ D is mid-point of BC.

$$\begin{aligned}D = \Big(\frac{2 + 10}{2}, \frac{(-6) + (-6)}{2}\Big) \\[1em] = \Big(\frac{12}{2}, \frac{-12}{2}\Big) \\[1em] = (6, -6).\end{aligned}$$

Hence, Option 3 is the correct option.

251 Mark · Multiple Choice Questions

The points A, B and C divide the line segment joining the points P(-3, 8) and Q(9, -4) into four equal parts. If A is nearest to P, then the coordinates of A are:

Show SolutionHide Solution↓

Given,

The points dividing PQ into four equal parts be A, B and C such that A is nearest to P.

Since the line segment PQ is divided into four equal parts, the point A divides PQ in the ratio 1 : 3.

The points A, B and C divide the line segment joining the points P(-3, 8) and Q(9, -4) into four equal parts. If A is nearest to P, then the coordinates of A are: Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{1 \times 9 + 3 \times (-3)}{1 + 3}, \frac{1 \times (-4) + 3 \times 8}{1 + 3}\Big) \\[1em] \Rightarrow \Big(\frac{9 - 9}{4}, \frac{-4 + 24}{4}\Big) \\[1em] \Rightarrow \Big(\frac{0}{4}, \frac{20}{4}\Big) \\[1em] \Rightarrow (0, 5).\end{aligned}$$

Hence, Option 2 is the correct option.

261 Mark · Multiple Choice Questions

The line 2x + y - 4 = 0 divides the line segment joining A(2, -2) and B(3, 7) in the ratio:

Show SolutionHide Solution↓

Let the required point be P(x, y) which divides A(2, -2) and B(3, 7) in the ratio k : 1.

The line 2x + y - 4 = 0 divides the line segment joining A(2, -2) and B(3, 7) in the ratio:Reflection, RSA Mathematics Solutions ICSE Class 10.

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values, we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{k \times 3 + 1 \times 2}{k + 1}, \frac{k \times 7 + 1 \times (-2)}{k + 1}\Big) \\[1em] \Rightarrow (x, y) = \Big(\frac{3k + 2}{k + 1}, \frac{7k - 2}{k + 1}\Big)\end{aligned}$$

Since P lies on the line 2x + y - 4 = 0, substituting the values of x and y:

$$\begin{aligned}\Rightarrow 2\Big(\frac{3k + 2}{k + 1}\Big) + \Big(\frac{7k - 2}{k + 1}\Big) - 4 = 0 \\[1em] \Rightarrow \frac{6k + 4 + 7k - 2}{k + 1} - 4 = 0 \\[1em] \Rightarrow \frac{13k + 2}{k + 1} = 4 \\[1em] \Rightarrow 13k + 2 = 4(k + 1) \\[1em] \Rightarrow 13k + 2 = 4k + 4 \\[1em] \Rightarrow 9k = 2 \\[1em] \Rightarrow k = \frac{2}{9} \\[1em] \Rightarrow k : 1 = \frac{2}{9} : 1 = 2 : 9.\end{aligned}$$

Hence, Option 4 is the correct option.

271 Mark · Multiple Choice Questions

The centre of the circle having end points of its one diameter as (-4, 2) and (4, -3) is:

Show SolutionHide Solution↓

Let the end points of the diameter be A(-4, 2) and B(4, -3). The centre of the circle is the mid-point of the diameter AB.

The centre of the circle having end points of its one diameter as (-4, 2) and (4, -3) is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{-4 + 4}{2}, \frac{2 + (-3)}{2}\Big) \\[1em] = \Big(\frac{0}{2}, \frac{-1}{2}\Big) \\[1em] = \Big(0, -\frac{1}{2}\Big).\end{aligned}$$

Hence, Option 3 is the correct option.

281 Mark · Multiple Choice Questions

A circle has its centre at (4, 4). If one end of a diameter is (4, 0), then the coordinates of the other end are:

Show SolutionHide Solution↓

Let one end of the diameter be A(4, 0) and the other end be B(x, y). Given that the centre of the circle is (4, 4), which is the mid-point of AB.

A circle has its centre at (4, 4). If one end of a diameter is (4, 0), then the coordinates of the other end are: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (4, 4) = \Big(\frac{4 + x}{2}, \frac{0 + y}{2}\Big) \\[1em] \Rightarrow 4 = \frac{4 + x}{2} \text{ and } 4 = \frac{y}{2} \\[1em] \Rightarrow x + 4 = 8 \text{ and } y = 8 \\[1em] \Rightarrow x = 8 - 4 = 4 \text{ and } y = 8.\end{aligned}$$

The coordinates of the other end of the diameter are (4, 8).

Hence, Option 2 is the correct option.

291 Mark · Multiple Choice Questions

The vertices of a parallelogram in order are A(1, 2), B(4, y), C(x, 6) and D(3, 5). Then (x, y) is:

Show SolutionHide Solution↓

In a parallelogram, the diagonals bisect each other. Therefore, the mid-point of AC = mid-point of BD.

The vertices of a parallelogram in order are A(1, 2), B(4, y), C(x, 6) and D(3, 5). Then (x, y) is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values, we get :

For diagonal AC :

$\text{Mid-point of AC} = \Big(\frac{1 + x}{2}, \frac{2 + 6}{2}\Big) = \Big(\frac{1 + x}{2}, 4\Big)$

For diagonal BD:

$\text{Mid-point of BD} = \Big(\frac{4 + 3}{2}, \frac{y + 5}{2}\Big) = \Big(\frac{7}{2}, \frac{y + 5}{2}\Big)$

Since both mid-points are equal, we equate their coordinates:

$$\begin{aligned}\Rightarrow \Big(\frac{1 + x}{2}, 4\Big) = \Big(\frac{7}{2}, \frac{y + 5}{2}\Big) \\[1em] \Rightarrow \frac{1 + x}{2} = \frac{7}{2}, 4 = \frac{y + 5}{2}\\[1em] \Rightarrow 1 + x = 7, y + 5 = 8 \\[1em] \Rightarrow x = 7 - 1, y = 8 - 5 \\[1em] \Rightarrow x = 6, y = 3.\end{aligned}$$

(x, y) = (6, 3).

Hence, Option 1 is the correct option.

301 Mark · Multiple Choice Questions

The fourth vertex D of a parallelogram ABCD whose three vertices are A(-2, 3), B(6, 7) and C(8, 3) is:

Show SolutionHide Solution↓

In a parallelogram, the diagonals bisect each other. Therefore, the mid-point of AC = mid-point of BD.

The fourth vertex D of a parallelogram ABCD whose three vertices are A(-2, 3), B(6, 7) and C(8, 3) is: Reflection, RSA Mathematics Solutions ICSE Class 10.

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

Substituting values, we get :

For diagonal AC:

$$\begin{aligned}\text{Mid-point of AC} = \Big(\frac{-2 + 8}{2}, \frac{3 + 3}{2}\Big) = \Big(\frac{6}{2}, \frac{6}{2}\Big) \\[1em] = (3, 3).\end{aligned}$$

Let point D be (x, y).

For diagonal BD:

$$\begin{aligned}\text{Mid-point of BD} = \Big(\frac{6 + x}{2}, \frac{7 + y}{2}\Big) \\[1em] \Rightarrow (3, 3) = \Big(\frac{6 + x}{2}, \frac{7 + y}{2}\Big) \\[1em] \Rightarrow 3 = \frac{6 + x}{2} \text{ and } 3 = \frac{7 + y}{2} \\[1em] \Rightarrow 6 = 6 + x \text{ and } 6= 7 + y \\[1em] \Rightarrow x = 0 \text{ and } y = 6 - 7 = -1.\end{aligned}$$

D = (x, y) = (0, -1).

Hence, Option 2 is the correct option.

311 Mark · Multiple Choice Questions

A(1, 4), B(4, 1) and C(x, 4) are the vertices of ΔABC. If the centroid of the triangle is G(4, 3), then x is equal to:

Show SolutionHide Solution↓

Given,

The vertices of the triangle be A(1, 4), B(4, 1) and C(x, 4). The centroid G of a triangle is given by the formula:

A(1, 4), B(4, 1) and C(x, 4) are the vertices of ΔABC. If the centroid of the triangle is G(4, 3), then x is equal to: Reflection, RSA Mathematics Solutions ICSE Class 10.

Centroid = $\Big(\frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3}\Big)$

Substituting the given values we get :

$$\begin{aligned}\Rightarrow (4, 3) = \Big(\frac{1 + 4 + x}{3}, \frac{4 + 1 + 4}{3}\Big) \\[1em] \Rightarrow (4, 3) = \Big(\frac{5 + x}{3}, \frac{9}{3}\Big) \\[1em] \Rightarrow (4, 3) = \Big(\frac{5 + x}{3}, 3\Big) \\[1em] \Rightarrow 4 = \frac{5 + x}{3} \\[1em] \Rightarrow 12 = 5 + x \\[1em] \Rightarrow x = 12 - 5 = 7.\end{aligned}$$

Hence, Option 3 is the correct option.

1Assertion-Reason Type Questions

Assertion (A): The coordinates of a point which divides a line segment joining the points (-3, 4) and (7, -6) in the ratio 1 : 2 internally are $\Big(\frac{1}{3}, \frac{2}{3}\Big)$.

Reason (R): The coordinates of the point which divides the line segment joining the points (x1, y1) and (x2, y2) internally in the ratio m : n are given by $\Big(\frac{mx_2 + nx_1}{m + n}, \frac{my_2 + ny_1}{m + n}\Big)$.

options

Show SolutionHide Solution↓

Let point P be (x, y), which divides the line segment joining the points (-3, 4) and (7, -6) in the ratio 1 : 2.

The coordinates of a point which divides a line segment joining the points (-3, 4) and (7, -6) in the ratio 1 : 2. Reflection, RSA Mathematics Solutions ICSE Class 10.

Given,

m1 : m2 = 1 : 2

By section-formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substitute values we get:

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{1(7) + 2(-3)}{1 + 2}, \frac{1(-6) + 2(4)}{1 + 2}\Big) \\[1em] = \Big(\frac{7 - 6}{3}, \frac{-6 + 8}{3}\Big) \\[1em] = \Big(\frac{1}{3}, \frac{2}{3}\Big).\end{aligned}$$

So, Assertion (A) is true.

The reason states the standard section formula, which is exactly the formula used to obtain the point in the Assertion.

So, Reason (R) is true and it is the correct explanation of Assertion (A).

Hence, Option 1 is the correct option.

2Assertion-Reason Type Questions

Assertion (A): The coordinates of one end of a diameter of a circle are (1, 4). If its centre is at (2, -3), then the coordinates of the other end of the diameter are (-3, -10).

Reason (R): The centre of a circle is equidistant from each end of a diameter.

options

Show SolutionHide Solution↓

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

We know that the centre is the mid-point of a diameter of a circle.

Given,

Centre = (2, -3)

One end of diameter = (1, 4)

Let the other end of the diameter be (a, b).

The coordinates of one end of a diameter of a circle are (1, 4). If its centre is at (2, -3), then the coordinates of the other end of the diameter are (-3, -10). Reflection, RSA Mathematics Solutions ICSE Class 10.

Substituting values, we get :

$$\begin{aligned}\Rightarrow (2, -3) = \Big(\frac{1 + a}{2}, \frac{4 + b}{2}\Big) \\[1em] \Rightarrow 2 = \frac{1 + a}{2} \text{ and } -3 = \frac{4 + b}{2} \\[1em] \Rightarrow 4 = 1 + a \text{ and } -6 = 4 + b \\[1em] \Rightarrow a = 3 \text{ and } b = -10.\end{aligned}$$

The correct coordinates of the other end are (3, -10).

So, Assertion (A) is false.

Since the centre is the mid-point of a diameter, it is equidistant from each end of the diameter.

So, Reason (R) is true.

Hence, Option 4 is the correct option.

3Assertion-Reason Type Questions

Assertion (A): If the points A(x, 1), B(8, 2), C(9, 4) and D(7, 3) are the vertices of a parallelogram, taken in order, then the value of x is 6.

Reason (R): Adjacent angles of a parallelogram are supplementary.

options

Show SolutionHide Solution↓

By mid-point formula,

(x, y) = $\Big(\frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2}\Big)$

If the points A(x, 1), B(8, 2), C(9, 4) and D(7, 3) are the vertices of a parallelogram, taken in order, then the value of x is 6. Reflection, RSA Mathematics Solutions ICSE Class 10.

Mid-point of AC :

$M_{AC} = \Big(\frac{x + 9}{2}, \frac{1 + 4}{2}\Big) = \Big(\frac{x + 9}{2}, \frac{5}{2}\Big)$

Mid-point of BD :

$M_{BD} = \Big(\frac{8 + 7}{2}, \frac{2 + 3}{2}\Big) = \Big(\frac{15}{2}, \frac{5}{2}\Big)$

Diagonals of a parallelogram bisect each other.

Thus,

Mid-point of AC = Mid-point of BD

$$\begin{aligned}\Rightarrow \Big(\frac{x + 9}{2}, \frac{5}{2}\Big) = \Big(\frac{15}{2}, \frac{5}{2}\Big) \\[1em] \Rightarrow \frac{x + 9}{2} = \frac{15}{2} \\[1em] \Rightarrow x + 9 = 15 \\[1em] \Rightarrow x = 15 - 9 = 6.\end{aligned}$$

So, Assertion (A) is true.

It is also true that the adjacent angles of a parallelogram are supplementary. However, the value of x is obtained using the property that the diagonals of a parallelogram bisect each other, not from the adjacent angles being supplementary.

So, Reason (R) is true, but it is not the correct explanation of Assertion (A).

Hence, Option 2 is the correct option.

4Assertion-Reason Type Questions

Assertion (A): The coordinates of the centroid of a triangle whose vertices are (-1, -4), (4, 3) and (6, -2) are (3, -1).

Reason (R): If the vertices of a triangle are (x1, y1), (x2, y2) and (x3, y3), then the coordinates of its centroid are $\Big(\frac{x_1 + x_2 + x_3}{2}, \frac{x_1 + x_2 + x_3}{2}\Big)$.

options

Show SolutionHide Solution↓

By the centroid formula,

$(x, y) = \Big( \frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3} \Big)$

The coordinates of the centroid of a triangle whose vertices are (-1, -4), (4, 3) and (6, -2) are (3, -1). Reflection, RSA Mathematics Solutions ICSE Class 10.

Substitute values we get,

$$\begin{aligned}\Rightarrow (x, y) = \Big( \frac{-1 + 4 + 6}{3}, \frac{-4 + 3 + (-2)}{3} \Big) \\[1em] \Rightarrow (x, y) = \Big( \frac{9}{3}, \frac{-3}{3} \Big) \\[1em] \Rightarrow (x, y) = (3, -1).\end{aligned}$$

So, Assertion (A) is true.

The correct centroid formula is $\Big(\frac{x_1 + x_2 + x_3}{3}, \frac{y_1 + y_2 + y_3}{3}\Big)$. The formula given in the Reason has the wrong denominator (2 instead of 3) and uses x-coordinates in place of the y-coordinates for the second term.

So, Reason (R) is false.

Hence, Option 3 is the correct option.

1Analytical and Application Based Questions

Determine the ratio in which the line y = 2 + 3x divides the line segment AB joining the points A(-3, 9) and B(4, 2).

Show SolutionHide Solution↓

By two point form,

Equation of line :

⇒ y - y1 = $\frac{y_2 - y_1}{x_2 - x_1}$(x - x1)

Equation of AB :

$$\begin{aligned}\Rightarrow y - 9 = \frac{2 - 9}{4 - (-3)}[x - (-3)] \\[1em] \Rightarrow y - 9 = \frac{-7}{4 + 3}[x + 3] \\[1em] \Rightarrow y - 9 = \frac{-7}{7}[x + 3] \\[1em] \Rightarrow y - 9 = -1[x + 3] \\[1em] \Rightarrow y - 9 = -x - 3 \\[1em] \Rightarrow y + x = -3 + 9 \\[1em] \Rightarrow x + y = 6.\end{aligned}$$

Solving equation y = 2 + 3x and x + y = 6 simultaneously,

⇒ x + y = 6 .......(1)

⇒ y = 2 + 3x .......(2)

Substituting value of y from equation (2) in (1), we get :

⇒ x + (2 + 3x) = 6

⇒ 4x + 2 = 6

⇒ 4x = 6 - 2

⇒ 4x = 4

⇒ x = $\frac{4}{4}$

⇒ x = 1.

Substituting value of x in equation (2), we get :

⇒ y = 2 + 3(1) = 2 + 3 = 5.

Let (1, 5) divide the line AB in the ratio k : 1.

By section formula,

(x, y) = $\Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big)$

Substituting values we get :

$$\begin{aligned}\Rightarrow (1, 5) = \Big(\frac{k \times 4 + 1 \times -3}{k + 1}, \frac{k \times 2 + 1 \times 9}{k + 1}\Big) \\[1em] \Rightarrow (1, 5) = \Big(\frac{4k - 3}{k + 1}, \frac{2k + 9}{k + 1}\Big) \\[1em] \Rightarrow 1 = \frac{4k - 3}{k + 1} \text{ or } 5 = \frac{2k + 9}{k + 1} \\[1em] \Rightarrow 1(k + 1) = 4k - 3 \text{ or } 5(k + 1) = 2k + 9 \\[1em] \Rightarrow k + 1 = 4k - 3 \text{ or } 5k + 5 = 2k + 9 \\[1em] \Rightarrow 4k - k = 1 + 3 \text{ or } 5k - 2k = 9 - 5 \\[1em] \Rightarrow 3k = 4 \text{ or } 3k = 4 \\[1em] \Rightarrow k = \frac{4}{3} \\[1em] \Rightarrow k : 1 = \frac{4}{3} : 1 = 4 : 3.\end{aligned}$$

Hence, the line y = 2 + 3x divides the line segment AB in the ratio 4 : 3.

2Analytical and Application Based Questions

In the given figure, if the line segment AB is intercepted by the y-axis and x-axis at C and D, respectively, such that AC : AD = 1 : 4 and D is the midpoint of CB. Find the coordinates of D, C and B.

In the given figure, if the line segment AB is intercepted by the y-axis and x-axis at C and D, respectively, such that AC : AD = 1 : 4 and D is the midpoint of CB. Find the coordinates of D, C and B. Maths Competency Focused Practice Questions Class 10 Solutions.
Show SolutionHide Solution↓

Let coordinates of C be (0, b) and D be (a, 0).

Given,

AC : AD = 1 : 4

Let AC = x and AD = 4x.

From figure,

⇒ AD = AC + CD

⇒ 4x = x + CD

⇒ CD = 4x - x = 3x.

AC : CD = 1 : 3.

By section formula,

$$\begin{aligned}\Rightarrow (x, y) = \Big(\frac{m_1x_2 + m_2x_1}{m_1 + m_2}, \frac{m_1y_2 + m_2y_1}{m_1 + m_2}\Big) \\[1em] \Rightarrow (0, b) = \Big(\frac{1 \times a + 3 \times -2}{1 + 3}, \frac{1 \times 0 + 3 \times 6}{1 + 3}\Big) \\[1em] \Rightarrow (0, b) = \Big(\frac{a - 6}{4}, \frac{0 + 18}{4}\Big) \\[1em] \Rightarrow (0, b) = \Big(\frac{a - 6}{4}, \frac{18}{4}\Big) \\[1em] \Rightarrow \frac{a - 6}{4} = 0 \text{ and } b = \frac{18}{4} \\[1em] \Rightarrow a - 6 = 0 \text{ and } b = \frac{9}{2} \\[1em] \Rightarrow a = 6 \text{ and } b = \frac{9}{2}.\end{aligned}$$

C = (0 , b) = $\Big(0, \frac{9}{2}\Big)$ and D = (6, 0).

Given, D is the mid-point of CB.

$$\begin{aligned}\therefore (6, 0) = \Big(\frac{0 + p}{2}, \frac{\frac{9}{2} + q}{2}\Big) \\[1em] \Rightarrow (6, 0) = \Big(\frac{p}{2}, \frac{9 + 2q}{2 \times 2}\Big) \\[1em] \Rightarrow (6, 0) = \Big(\frac{p}{2}, \frac{9 + 2q}{4}\Big) \\[1em] \Rightarrow \frac{p}{2} = 6 \text{ and } \frac{9 + 2q}{4} = 0 \\[1em] \Rightarrow p = 12 \text{ and } 9 + 2q = 0 \\[1em] \Rightarrow p = 12 \text{ and } 2q = -9 \\[1em] \Rightarrow p = 12 \text{ and } q = -\frac{9}{2} \\[1em] \Rightarrow B = (p, q) = \Big(12, -\frac{9}{2}\Big).\end{aligned}$$

Hence, coordinates of B = $\Big(12, -\frac{9}{2}\Big), C = \Big(0, \frac{9}{2}\Big)$ and D = (6, 0).

Press ↓ to reveal a solution and move to the next question. Back to RS Aggarwal Mathematics.

Free sample bank