i can't post the complete solution now. my one hour will be wasted typing the same. :P :D
the hint is sufficient i guess.!
tanθ.tanφ=√(p-q)/p+q),show that (p-qcos2θ)(p-qcos2φ) is independent of φ and θ
use cos2θ = 1-tan2θ / 1+tan2θ, upon further simplification u will get the term independent of the angles.
i can't post the complete solution now. my one hour will be wasted typing the same. :P :D
the hint is sufficient i guess.!