∠1 and ​ ∠2 ​ are vertical angles. ∠2 ​ has a measure of 63°. What is the measure of ​ ∠1 ​?Enter your answer in the box.

Vertical angles share a vertex, or basically a point, and are the opposite angles formed by two intersecting lines. They have the same angle measure (they're congruent).

So, if m∠1 = 63°, then m∠2 = 63°.