That " " looks peculiar. Is it really [tex]sin^2(\theta)[itex] or did you mean to write "[tex]sin(\theta)cos(\theta)[/itex]"?

Either way, it's a pretty straightforward integral.

Of course, the integral of "[tex]cos(\phi)[/itex]" is " " and to integrate " " use the identity .

If you intended rather than ,

Of course, the integral of " " is " " and to integrate " " use the substitution .