For this problem I would use sec2θ = 1 + tan2θ. The problem simplifies rather nicely in a few steps. If you need more help, let us know.
In the future, to get you started, look for trig functions in the problem and see if there is a trig identity that has most (or all, as in this case) of it. For this problem in particular, tangent and secant raised to powers is a dead giveaway. After working problems like this for a while you will start looking for things like this.