## Geometry and Trigonometry## Basics of Geometry |

## How are the simplest angles classified? |

Angles are usually expressed in terms of “rotation,” in which a full rotation is equal— in most cases—to a 360 degree circle. Half of a full rotation is called a *straight angle;* a quarter of a full rotation is called a *right angle* (90 degrees). An angle less than a right angle is called an *acute angle;* an angle greater than a right angle is called an *obtuse angle.*