An angle is defined as the amount of rotation between two rays. The point where the rays start is called the vertex. There are two systems for measuring angles in mathematics: degrees and radians. While the degree angle system is often used to introduce concepts in math, the radian system eventually becomes the preferred unit for measuring angles[1].

Types of Angles

Perpendicular Angle

A perpendicular angle is equal to a quarter of a full rotation.

Acute Angle

An acute angle is defined as an angle smaller than a perpendicular angle.

Obtuse Angle

An angle greater than 90 degrees.


  1. Radians Versus Degrees
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