jcaron2
Jan 30, 2011, 07:50 AM
You can factor the difference of two cubes as follows:
a^3-b^3=(a-b)(a^2+ab+b^2)
So if you factor out the left side of the equation, notice that you'll end up with a sin^2(x) and a cos^2(x) in the second set of parentheses. Those will add together to become 1.
See if you can take it from there.