Oh, sorry. I got to include the steps.
f'(theta) = 2sec(theta)tan(theta) + sec^2(theta)
I set it equal to zero, factored out a sec(theta). I was left with 2 equations: sec(theta)=0 and 2tan(theta) + sec(theta) = 0 =>2tan(theta) = -sec(theta) {I didn't mean sin before...I meant sec}