C. $\frac{\tan^{2}\alpha -\tan^{2}\beta }{\tan^{2}\alpha.\tan^{2}\beta }= \frac{\sin^{2}-\sin^{2}\beta }{\sin^{2}\alpha .\sin^{2}\beta }$
B. $\frac{\sin^{2}\alpha }{\cos^{2}\beta }+ \tan^{2}\beta .\cos^{2}\alpha = \sin^{2}\alpha +\tan^{2}\beta $
A. $(\frac{\sin\alpha +\cot\alpha}{1+\sin\alpha\tan\alpha})^{2}= \frac{\sin^{2}\alpha+\cot^{2}\alpha}{1+\sin^{2}\alpha.\tan^{2}\alpha}$
