The COSINE of an arbitary angle in a coordinate system is the ratio between the abscissa of a point on that angle's terminal leg and the radius vector to that point.
| Function / Angle | 0° | 30° | 45° | 60° | 90° | 180° | 270° | 360° |
| Cosine | 1 |  |
 |
1/2 | 0 | -1 | 0 | 1 |