The diogonals AC and BD of a parallelogram ABCD bisect each other at O. A line segment XY through O has its end-points on the pposite sides AB and CD. Is XY also bisected at O.

Given : ABCD is a parallelogram. Diagonals AB and BD intersect at O. XY passes through O and intersects AB and CD in X and Y respectively.

To Prove : OX = OY

Proof : 

We know that, the diagonals of the parallelogram bisect each other.

∴ OA = OC

In ΔAOX and ΔCOY,

∠OAX = ∠OCY    (Pair of alternate angles)

OA = OC

∠AOX= ∠COY     (Vertically opposite angles)

∴ΔAOX ΔCOY   (ASA congruence Criterion)

⇒ OX = OY    (CPCT)

Thus, XY is bisected at O.

  • 0
What are you looking for?