One thing I can recommend is to use symbols until you have a quadratic to solve and then plug in numbers. It's easier to spot mistakes and somebody trying to help you can follow the equations without having to do arithmetic in their heads. It always helps me but I hate arithmetic ;)
I wonder if you could substitute something for [tex]sec^{2} \theta[/tex]. There might be a trig identity. It might even involve [tex]tan^{2} \theta[/tex] which would be sweet 'cause then you'd have a quadratic for the tangent.
