Question

(ii) If tan2 x = 2 tan2 y + 1, show that cos 2x + sin? y = 0.​

Answer 1

Answercos2θ+sin2ϕ=1−tan2θ1+tan2θ+sin2ϕ

=1−(2tan2ϕ+1)1+(2tan2ϕ+1)+sin2ϕ

=−tan2ϕ1+tan2ϕ+sin2ϕ=−tan2ϕsec2ϕ+sin2ϕ=0