Question

which angle is complementary to ∠4?

Explanation:

Step1: Recall complementary - angle definition

Two angles are complementary if their sum is 90 degrees.

Step2: Analyze the given angles

We see that $\angle3+\angle4 = 90^{\circ}$ (since the right - angle is divided into $\angle3$ and $\angle4$).

Answer:

$\angle3$