Question

which angle is supplementary to ∠1?

Explanation:

Step1: Recall supplementary - angle definition

Two angles are supplementary if their sum is 180 degrees. Adjacent angles that form a straight - line are supplementary.

Step2: Identify adjacent angle to ∠1

∠1 and ∠3 form a straight - line. So, ∠3 is supplementary to ∠1.

Answer:

∠3