Given f(x) = xcosx + xsinx find the horizontal tangent points in [0,2pi). Okay, I found the derivative f'(x) = -xsinx + cosx + xcosx + sinx. I set f'(x) = 0, but I can't seem to factor this equation. I've tried everything I know. If anyone can tell me how to solve this, it would be greatly appreciated. Thank you