cosec A - 2 2A A = - Vidyadip

MCQ

${\rm{cosec }}A - 2\cot 2A\cos A = $

✓
$2\sin A$
B
$\sec A$
C
$2\cos A\cot A$
D
None of these

✓

Answer

Correct option: A.

$2\sin A$

a
(a) ${\rm{cosec}}\,A - 2\cot 2A\cos A $

$= \frac{1}{{\sin A}} - \frac{{2\cos A\cos 2A}}{{\sin 2A}}$

$ = \frac{1}{{\sin A}} - \frac{{2\cos A\cos 2A}}{{2\sin A\cos A}} $

$= \frac{{1 - \cos 2A}}{{\sin A}} $

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

$ = 2\sin A$.

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