To solve the question of when two acute angles are called complementary, we need to understand the definition of complementary angles.
1. Understanding Complementary Angles:
Complementary angles are two angles whose measures add up to a specific value.
2. Sum of Complementary Angles:
By definition, the sum of two complementary angles is a specific angle measurement.
3. Identifying the Specific Angle:
A right angle is measured as 90°. Therefore, two angles are complementary if their measures add up to a right angle.
So, two acute angles are called complementary if their sum is a right angle.
Hence, the correct answer is:
- A right angle
