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Mathematics

The point P divides the line segment joining the point (1, 2) and (-1, 2) internally in the ratio 1 : 2.

Assertion (A) : The co-ordinates of point P = (1, 6)

Reason (R) : If point P divides the line segment joining the points (x1, y1) and (x2, y2) in the ratio m1 : m2 then :

P = (m1x2+m2x1m1+m2,m1y2+m2y1m1+m2)\Big(\dfrac{m1x2 + m2x1}{m1 + m2}, \dfrac{m1y2 + m2y1}{m1 + m2}\Big)

  1. A is true, R is false.

  2. A is false, R is true.

  3. Both A and R are true and R is correct reason for A.

  4. Both A and R are true and R is incorrect reason for A.

Section Formula

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Answer

We know that,

If point P divides the line segment joining the points (x1, y1) and (x2, y2) in the ratio m1 : m2, then :

Co-ordinates of P = (m1x2+m2x1m1+m2,m1y2+m2y1m1+m2)\Big(\dfrac{m1x2 + m2x1}{m1 + m2}, \dfrac{m1y2 + m2y1}{m1 + m2}\Big)

So, reason (R) is true.

Here, (x1, y1) = (1, 2) and (x2, y2) = (-1, 2)

m1 : m2 = 1 : 2

Substituting the values, we get :

P=[1×(1)+2×11+2,1×2+2×21+2]=(1+23,2+43)=(13,63)=(13,2)\Rightarrow \text{P} = \Big[\dfrac{1\times (-1) + 2\times 1}{1 + 2}, \dfrac{1 \times 2 + 2 \times 2}{1 + 2}\Big]\\[1em] = \Big(\dfrac{-1 + 2}{3}, \dfrac{2 + 4}{3}\Big)\\[1em] = \Big(\dfrac{1}{3}, \dfrac{6}{3}\Big)\\[1em] = \Big(\dfrac{1}{3}, 2\Big)\\[1em]

So, assertion (A) is false.

Hence, option 2 is the correct option.

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