MCQ
$\tan \left( {\frac{\pi }{4} + \theta } \right) - \tan \left( {\frac{\pi }{4} - \theta } \right) = $
  • $2\tan 2\theta $
  • B
    $2\cot 2\theta $
  • C
    $\tan 2\theta $
  • D
    $\cot 2\theta $

Answer

Correct option: A.
$2\tan 2\theta $
a
(a) $\tan \left( {\frac{\pi }{4} + \theta } \right) - \tan \left( {\frac{\pi }{4} - \theta } \right) $

$= \frac{{1 + \tan \theta }}{{1 - \tan \theta }} - \frac{{1 - \tan \theta }}{{1 + \tan \theta }}$

$ = \frac{{4\tan \theta }}{{1 - {{\tan }^2}\theta }} $

$= 2\left( {\frac{{2\tan \theta }}{{1 - {{\tan }^2}\theta }}} \right) $

$= 2\tan 2\theta $.

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