Question

if 2 lines intersect prove that the vertically opposite angles are
equal.​

Answer 1

Step-by-step explanation:

Let AB & CD be two lines

∠1+∠4=180

∘

(CD is a st. line)

∠4+∠3=180

∘

(AB is a st. line)

∠1+∠4=∠4+∠3

∠1=∠3 similarly ∠2=∠4

thus proved