Question

f(α)=1-tanα/1+tanα then prove that f(π/4-α)=tanα​

Answer 1

$f( \alpha ) = \tan( \frac{\pi}{4} - \alpha )$

$f( \frac{\pi}{4} - \alpha ) = \tan( \frac{\pi}{4} - \frac{\pi}{4} + \alpha )$

$= \tan( \alpha )$