Which trigonometric function is an odd function and why? The cosine function is odd because it is represented by the x-coordinate of the points on the unit circle, and therefore cos(x) = cos(-x).

The sine function is odd because it is represented by the y-coordinate of the points on the unit circle, and therefore sin(-x) = - sin(x).

The cosine function is odd because it is represented by the x-coordinate of the points on the unit circle, and
therefore cos(-x) = cos(x)

The sine function is odd because it is represented by the y-coordinate of the points on the unit circle, and therefore sin(x) = sin(-x).