Question

Prove that if the sum of two adjacent angles is 180 degree then their two common arms are of two opposite rays​

Answer 1

Answer:

If the sum of two adjacent angles is 1800, then the non-common arms of the angles form a line. ... Note that ∠1 and ∠2 form a pair of vertically opposite angles. Similarly, ∠3 and ∠4 form another pair of vertically opposite angles.