Question

How do you find the antiderivative of `cos pi x`?

Answer 1

`intcospixdx=(sinpix)/pi+"c"`

Explanation:

For the integrand `cospix`, let `u=pix` and `du=pidx`. Then

`intcospixdx=1/piintcosudu=sinu/pi+"c"=(sinpix)/pi+"c"`