Question

which angle is vertical to ∠1?

Explanation:

Step1: Recall vertical - angle definition

Vertical angles are formed when two lines intersect. They are opposite each other and are equal in measure.

Step2: Identify vertical angle to ∠1

In the given figure, when two lines intersect, ∠1 and ∠4 are opposite each other. So, ∠4 is vertical to ∠1.

Answer:

∠4