Question

other than itself, which angle is congruent to ∠1?

Explanation:

Step1: Recall vertical angles property

Vertical angles are congruent. Vertical angles are opposite angles formed by the intersection of two lines.

Step2: Identify vertical angle of ∠1

Looking at the diagram, ∠3 is opposite to ∠1. So, ∠1 and ∠3 are vertical angles.

Answer:

∠3