Question

How do you find the derivative of `cos^3(u)`?

Answer 1

`-3cos^2(u)sin(u)`

Explanation:

The law for deriving the power of a function is the following:

`d/{du} f^n(u) = n f^{n-1}(u) * f'(u)`.

Of course, in your case `n=3`, and `f'(u)=-sin(u)`.

So, the result becomes

`d/{du} cos^3(u) = 3cos^2(u) * (-\sin(u))`