Sum of Measures of Two Angles Forming a Right Angle
To understand the relationship between the sum of measures of two angles forming a right angle, we need to consider the definition of a right angle. A right angle measures 90 degrees, which is one-fourth of a complete revolution or a quarter of a circle.

Explanation
- When the sum of measures of two angles is that of a right angle (90 degrees), it means that the angles are complementary.
- Complementary angles are two angles whose measures add up to 90 degrees.
- Therefore, if the sum of measures of two angles is equal to 90 degrees, each angle is said to be a complementary angle.
- In simpler terms, when two angles add up to form a right angle, they are considered complementary to each other.

Example
For example, let's consider two angles: Angle A and Angle B. If Angle A measures 30 degrees, then Angle B must measure 60 degrees so that their sum equals 90 degrees, forming a right angle. In this case, Angle A and Angle B are complementary angles.

Conclusion
In conclusion, when the sum of measures of two angles is that of a right angle, each angle is considered to be a complementary angle. Complementary angles always add up to 90 degrees, forming a right angle. This relationship between angles is crucial in geometry and helps us understand the properties of angles in various shapes and figures.