Question

What is the derivative of `f(t)=cos^2(3t+5)`?

Answer 1

I found: `f'(t)=-6cos(3t+5)sin(3t+5)`

Explanation:

I would use the Chain Rule to deal with the sequence of functions: `()^2` then `cos` and then `(3t+5)`: so you get:
`f'(t)=2cos(3t+5)*color(red)(-sin(3t+5))*color(blue)(3)=`
`=-6cos(3t+5)sin(3t+5)`