Question

Please answer with full explanation
Find weather tanA^2/1+tanA^2 =sinA^2 is an identity or not.

Answer 1

$LHS = \frac{tan^2A}{1+tan^2A}$

$= \frac{tan^2A}{Sec^2A}$

$= tan^2A*Cos^2A$

$= \frac{Sin^2A}{Cos^2A}Cos^2A$

$= Sin^2A = RHS$

Hence it is true

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