Question

1. (20) if the exterior sides of adjacent angles are perpendicular, the angles are ______________. a. right angles b. complementary c. congruent d. supplementary e. vertical

Explanation:

Step1: Recall angle - relationship definitions

Let the two adjacent angles be $\angle A$ and $\angle B$. The exterior sides of the adjacent angles are perpendicular, which means the angle formed by the exterior - sides is a right - angle ($90^{\circ}$).

Step2: Use the angle - sum property of adjacent angles

The sum of the two adjacent angles $\angle A+\angle B = 180^{\circ}-90^{\circ}=90^{\circ}$.
Two angles whose sum is $90^{\circ}$ are called complementary angles.

Answer:

B. complementary