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Circles

Question
CBSEENMA9002740

ABCD is a parallelogram and line segments AX, CY bisect the angles A and C respectively. Show that AX || CY.

Solution

Given: ABCD is a parallelogram and line segments AX, CY bisect the angles A and C respectively.
To Prove: AX || CY.
Proof: ∵ ABCD is a parallelogram.
∴ ∠A = ∠C    | Opposite ∠s

rightwards double arrow space space space space 1 half angle straight A equals 1 half angle straight C
| ∵ Halves of equals are equal
⇒ ∠1 = ∠2    ....(1)
| ∵ AX is the bisector of ∠A and CY is the bisector of ∠C
Now, AB || DC and CY intersects them
∴ ∠2 = ∠3    ...(2)
| Alternate interior ∠s
From (1) and (2), we get
∠1 = ∠3
But these form a pair of equal corresponding angles
∴ AX || CY.