Question

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

Explanation:

Step1: Recall angle congruence rules

When two lines intersect, vertical angles are congruent, and also, if there are angle bisectors or equal angle formations from a common vertex with equal angle measures, those angles are congruent. Looking at the diagram, we analyze the angles around the intersection point.

Step2: Identify congruent angle to ∠1

From the diagram, ∠1 and ∠3 seem to be formed in a way that their angle measures are equal (either as vertical angles or due to the symmetry of the angle divisions). Also, checking the other angles, ∠1 should be congruent to ∠3 (by the properties of angles formed at a point with equal - measure angle divisions or vertical - like angle relationships in the given diagram).

Answer:

$\angle3$