It's
I've attached a picture, I have a good handle on using the fundamental theorem of calculus to find derivatives of functions, but this one is just stumping me for some reason. First I tried doing it as is, then I literally had no idea what I could be doing wrong so I tried negating it so that the sin is on top, but that makes no difference. Could someone help a brotha out with this toughie? The thing that's throwing me is the fact that there isn't a real number on the top or bottom of the integral, they're both trig functions. I didn't think this would affect how to go about solving the problem but it must somehow...