Question

if two lines intersect each other at a point , then show that their vertically opposite angles are equal​

Answer 1

$\bold{answer}$

If two lines i.e. AB & CD intersect each other. They have two pair of opp. angles.

i.e.

∠AOC,∠DOB,∠AOB,∠COB.

To prove :- ∠AOC=∠DOB & ∠AOD=∠COB

Proof :-

∠AOC+∠AOD=180° [linear pair] ___(1)

∠AOD+∠BOD=180° [linear pair] ___(2)

from eq. (1) & (2)

∠AOC+∠AOD=∠AOD+∠BOD

i.e. [∠AOC=∠BOD]

Similarly [∠AOD=∠COB] Hence proved.