Answers by visitors named: Kiely

I am completely stumped. I've never worked with ^4 before and I don't know how to factor it out.

I got up to 1-sin^2x - sin^2y + sin^2xsin^y +sin^2x-sin^2xsin^2y + sin^2y-sin^2ysin^x. I don't know if that's right or wrong.