What is a 90-degree angle called?

A 90-degree angle is called a right angle. In geometry, a right angle is defined specifically as an angle that measures exactly 90 degrees. It serves as a standard reference point for various geometric ideas and constructions. Right angles are commonly found in many shapes, such as squares and rectangles, and they are fundamental in the creation of perpendicular lines.

Understanding the definition and characteristics of different types of angles is crucial. An acute angle is one that measures less than 90 degrees, while an obtuse angle measures more than 90 degrees but less than 180 degrees. A straight angle, on the other hand, measures exactly 180 degrees, representing a straight line. Thus, the terminology related to angles is essential for clear communication and understanding in mathematics and related fields.