Primitive of Square of Cosine Function

Theorem

 * $\ds \int \cos^2 x \rd x = \frac x 2 + \frac {\sin 2 x} 4 + C$

where $C$ is an arbitrary constant.

Also presented as
Some sources present this as:


 * $\ds \int \cos^2 x \rd x = \frac 1 2 \paren {x + \frac {\sin 2 x} 2} + C$