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Mathematics

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 (13,23)\Big(\dfrac{1}{3}, \dfrac{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 (mx2+nx1m+n,my2+ny1m+n)\Big(\dfrac{mx2 + nx1}{m + n}, \dfrac{my2 + ny1}{m + n}\Big).

  1. A is true, R is false

  2. A is false, R is true

  3. Both A and R are true

  4. Both A and R are false

Section Formula

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Answer

Let point P be (x, y), which divides 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) = (m1x2+m2x1m1+m2,m1y2+m2y1m1+m2)\Big(\dfrac{m1x2 + m2x1}{m1 + m2}, \dfrac{m1y2 + m2y1}{m1 + m2}\Big)

Substitute values we get:

(x,y)=(1(7)+2(3)1+2,1(6)+2(4)1+2)=(763,6+83)=(13,23).\Rightarrow (x, y) = \Big(\dfrac{1(7) + 2(-3)}{1 + 2}, \dfrac{1(-6) + 2(4)}{1 + 2}\Big) \\[1em] = \Big(\dfrac{7 - 6}{3}, \dfrac{-6 + 8}{3}\Big) \\[1em] = \Big(\dfrac{1}{3}, \dfrac{2}{3}\Big).

So, Assertion is true.

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 (mx2+nx1m+n,my2+ny1m+n)\Big(\dfrac{mx2 + nx1}{m + n}, \dfrac{my2 + ny1}{m + n}\Big).

So, reason is true.

Both A and R are true.

Hence, Option 3 is the correct option.

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