Unit Circle Trigonometry

Description

This figure illustrates the trigonometry of the unit circle that corresponds to the circle definitions of the trigonometric functions. The circle definitions of sine and cosine are shown below:

Substituting into the definitions we can see the relationship between the functions and the point on the unit circle defined by the angle (theta). The coordinate of the point is equal to the sine of the angle and the coordinate of the point is equal to the cosine of the angle.

Figure