\(\frac{1+tan^2A}{1+cot^2A}\) =
1+tan2A1+cot2A =1+tan2A1+1tan2A =1+tan2Atan2A+1tan2A =(1+tan2A)(tan2A)(tan2A+1) = tan2A.
1tan3A−tanA−1cot3A−cotA=