Question

How do you find the antiderivative of `cos(2x)`?

Answer 1

`=1/2sin(2x)+C`

Explanation:

`intcos(2x)dx`

Let `u=2x`
`(du)/(dx)=2`
`(du)/2=dx`

Substitute in u:
`intcos(u)(du)/2`
`=1/2intcos(u)du`
`=1/2sinu+C`

Re-substitute the value of u:
`=1/2sin(2x)+C`