Verifying identies

As usual - first thing is to convert the csc(x) function to it's sine equivalent. Then apply the identity for sin(2x) - if you don't know it off the top of your head you need to memorize it. Finally look for other identities that can simplify things - one of the most common that shows up in these sorts of problems is sin^2x + cos^2x = 1, and its alternative forms such as sin^2x = 1 - cos^2x.