Question

1. definition of complementary angles: if (mangle1 + mangle2 = 90^{circ}), then ____________

Explanation:

Step1: Recall complementary - angle concept

By the definition of complementary angles, if the sum of the measures of two angles is 90°, then the two angles are complementary.

Answer:

$\angle1$ and $\angle2$ are complementary angles.