It is difficult to differentiate this function. It is not in the list of standard functions. Furthermore, there is a product of two trigonometric functions and we do not know how to differentiate this. Finally, the trigonometric functions have an argument .
Yet is appears quite simple to differentiate this function by applying one of the so-called double-angle formulas, i.e. by applying the trigonometric formula:
So the original function becomes:
which is quite easy to differentiate: