Angle


An angle is considered as the figure obtained by rotating a given ray about its end-point.

The revolving ray is called the generating line of the angle. The initial position OA is called the initial side and the final position OB is called the terminal side of the angle and the end point O about which the ray rotates is called the vertex of the angle.

The measure of an angle is the amount of rotation from the initial side to the terminal side.