Chapter 7 · Question 6

Find the point dividing (1,2)(1,2) and (7,8)(7,8) internally in the ratio 2:12:1.

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Q6

Find the point dividing (1,2)(1,2) and (7,8)(7,8) internally in the ratio 2:12:1.

Answer Revealed
Direct Answer:
Using section formula, x=2(7)+1(1)3=5x=\frac{2(7)+1(1)}{3}=5, y=2(8)+1(2)3=6y=\frac{2(8)+1(2)}{3}=6. The point is (5,6)(5,6).

Simple Explanation

Cross multiply with the ratio. The point is (5,6)(5,6).

Exam-Ready Structure

Let A(1,2)A(1,2) and B(7,8)B(7,8), and ratio AP:PB=2:1AP:PB=2:1. Then P=(27+112+1,28+122+1)=(153,183)=(5,6)P=\left(\frac{2\cdot7+1\cdot1}{2+1},\frac{2\cdot8+1\cdot2}{2+1}\right)=\left(\frac{15}{3},\frac{18}{3}\right)=(5,6).

Key Points

  • Using section formula, x=2(7)+1(1)3=5x=\frac{2(7)+1(1)}{3}=5, y=2(8)+1(2)3=6y=\frac{2(8)+1(2)}{3}=6.
  • Use the NCERT formula or theorem carefully.
  • Write units and final conclusion where applicable.