MCQ
$\frac{{\sin 3A - \cos \left( {\frac{\pi }{2} - A} \right)}}{{\cos A + \cos (\pi + 3A)}} = $
  • A
    $\tan A$
  • B
    $\cot A$
  • C
    $\tan 2A$
  • $\cot 2A$

Answer

Correct option: D.
$\cot 2A$
d
(d) $\frac{{\sin 3A - \cos \left( {\frac{\pi }{2} - A} \right)}}{{\cos A + \cos (\pi + 3A)}}$

$ = \frac{{\sin 3A - \sin A}}{{\cos A - \cos 3A}}$

$=\frac{{2\cos 2A\sin A}}{{2\sin 2A\sin A}}$

$= \frac{{\cos 2A}}{{\sin 2A}} = \cot 2A$.

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