Angle

An angle is defined as the amount of rotation between two rays.
Figure 1: Angle

An angle is defined as the amount of rotation between two rays. There are two systems for measuring angles in mathematics: degrees and radians. A full rotation in degrees is . A full rotation in radians is (tau) radians or approximately radians. For higher level math, radians are the preferred system to measure angles[1].

Types of Angles

Acute Angle
Acute Angle | Concept

An acute angle is an angle that is smaller than 90 degrees or PI fourths.

Obtuse Angle
Obtuse Angle | Concept

An obtuse angle is an angle that is larger than 90 degrees or PI fourths.

Perpendicular Angle
Perpendicular Angle | Concept

A Perpendicular angle, sometimes also referred to as a square angle, is exactly 90 degrees or PI fourths.

Related Angles

Complementary Angles
Complementary Angles | Notation

Complementary angles can visually be denoted as two angles who sum to a perpendicular or square angle.

Supplementary Angles
Supplementary Angles | Notation

Supplementary angles can visually be denoted as two angles who sum to 180 degrees or PI degrees.

Degrees

The degree angle system divides a full rotation into degrees.

This figure depicts how the degrees system measures angles where one full rotation is 360 degrees.
Figure 2: Degree Angle System

Radians

The radian angle system is used in higher level math to replace the degree angle system. A full rotation in radians is equal to (tau) radians.

Radian Angle System
Figure 3: Radian Angle System

references

  1. Radians Versus Degrees
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