So I've hit a wall, and as with other times I've posted, I'm really only looking for the "kick-off" step for this problem: I have tried using the fact that the integrand is really a half-angle in disguise, but that leads to: which seems more complicated than the original problem. I've also tried to replace either the sin or cos term with 1+ etc., but that quickly makes the problem more complicated, or lands me back at square one. Thanks in advance for any and all help.