Integrate cos(2x)

The intergral for cosx is sinx, but '2x' must be considered.

When differentiating a sinx/cosx function, the '2x' would be differentiated separately

and placed in the front (multipling). So when intergating you do the opposite and divide.

Therefore the intergral is 1/2sin(2x). You can check by differentiating 1/2sin(2x).