You can draw an angle in standard position by positioning its vertex at the origin and one "ray" on the positive x-axis. The ray on the x-axis is called the initial side and the other ray is called the terminal side.
An angle is then measured POSITIVE for a counterclockwise rotation and NEGATIVE for a clockwise rotation:
When two angles have the same initial and terminal sides, they are said to be coterminal angles.
Angles of −315° and 45° are coterminal angles.