Question

Prove that vertically oppsite angles are equal

Answer 1

If two lines are intersect each other, then the vertically opposite angles are equal.

Given: Two lines AB and CD intersecting at point O.

To prove: Vertically opposite angles are equal,i.e.,

angle AOC = angle BOD

and angle AOD = angle BOC

Proof: On line AB,

By linear pair,

angle AOC + angle BOC = 180° .......(1)

On line CD,

By linear pair,

angle AOD + angle AOC = 180° .......(2)