Question

which angle is complementary to ∠1?

Explanation:

Step1: Recall complementary - angle definition

Two angles are complementary if their sum is 90 degrees.

Step2: Analyze the given figure

In the figure, we can see that $\angle1+\angle2 = 90^{\circ}$ (since the angle between the two lines is a right - angle).

Answer:

$\angle2$