I can look into that. I had figured that 7.3 would be out by the time they worked this lab. This is one of the more difficult things with Sympy as well since its core features are still developing a great deal. It struck me as very odd that it couldn't simplify this one because, if you think about it for a minute, it is actually very easy to simplify. Just apply the double angle identity for sin(2x), factor and it is (cos^2(x)+sin^2(x))^3. I can fish around for other examples though.