Mathematics · Coordinate Geometry · NCERT Examples

Example 10

A complete, independently verified solution for NCERT Example 10.

Mathematics · Chapter 7 · NCERT Examples

Verified NCERT questions and solutionsSolutions are checked independently and follow the supplied NCERT chapter edition.

NCERT Example

Example 10

If A(6, 1), B(8, 2), C(9, 4) and D(p, 3) are the vertices of a parallelogram in order, find p.

Solution

Board-exam working:

The diagonals of a parallelogram bisect each other. Therefore, the midpoint of AC equals the midpoint of BD.

Midpoint of AC:

(6+92,1+42)=(152,52)\left(\frac{6+9}{2},\frac{1+4}{2}\right)=\left(\frac{15}{2},\frac52\right)

Midpoint of BD:

(8+p2,2+32)=(8+p2,52)\left(\frac{8+p}{2},\frac{2+3}{2}\right)=\left(\frac{8+p}{2},\frac52\right)

Equating the x-coordinates:

152=8+p2\frac{15}{2}=\frac{8+p}{2}
15=8+p15=8+p
p=7p=7

Final answer

p = 7.

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