tan2 A−12tanA\frac{\tan ^{2} \mathrm{~A}-1}{2 \tan A}2tanAtan2 A−1
2sinAcosAcos2A−sin2A\frac{2 \sin A \cos A}{\cos ^{2} A-\sin ^{2} A}cos2A−sin2A2sinAcosA
2tanA1+tan2A\frac{2 \tan A}{1+\tan ^{2} A}1+tan2A2tanA
1−tanA1+tanA\frac{1-\tan A}{1+\tan A}1+tanA1−tanA