Question

given: ∠1≅∠2

1. how would you prove that ∠1 = ∠4?

corresponding angles are supplementary.
corresponding angles are congruent.
vertical angles are supplementary.
vertical angles are congruent.

Explanation:

∠1 and ∠4 are vertical - angles. By the vertical - angles theorem, vertical angles are congruent.

Answer:

D. Vertical angles are congruent.