Question

Prove that if∠ 1 ≅ ∠2, then ∠2 ≅ ∠3. what is m∠1?

Answer 1

We see that angle 1 and angle 2 are equal.

By the vertical angle theorem, the opposite (vertical) angles of two intersecting lines are congruent, we see that angle 1 and angle 3 must be equal. Since angle 1 and angle 2 are equal, then angle 2 and angle 3 are equal.

And for angle 1, it must be 90 degrees, because if it was any other angle measure, angle 1 and angle 2 could never be equal