coterminal angles | The description of two angles drawn in standard position that share their terminal side. |
initial side | The stationary ray that forms an angle in standard position and lies on the positive x-axis. |
reference angle | The angle formed by the terminal side of an angle in standard position and the x-axis, whose measure is between 0° and 90°. |
standard position | The placement of an angle upon a set of coordinate axes with its vertex at the origin, its initial side placed along the positive x-axis, and a directional arrow pointing to the angle’s terminal side. |
terminal side | The ray that has been rotated around the origin to form an angle with the stationary ray that is the initial side of the angle. |
unit circle | A circle centered at the origin that has radius 1. |