# Integration of Cos Squared x

In this tutorial we shall drive the integral of cosine squared x.

The integration of the form

This integral cannot be evaluated by direct formula of integration, so using trigonometric identity of half angle ${\cos ^2}x = \frac{{1 + \cos 2x}}{2}$, we have

Using the integral formula $\int {\cos kxdx = \frac{{\sin kx}}{k} + c}$, we have