MCQ
$\frac{1}{4}\left[ {\sqrt 3 \cos 23^\circ - \sin 23^\circ } \right] = $
  • A
    $\cos 43^\circ $
  • B
    $\cos 7^\circ $
  • C
    $\cos 53^\circ $
  • None of these

Answer

Correct option: D.
None of these
d
(d) $\frac{1}{4}\{ \sqrt 3 \cos {23^o} - \sin {23^o}\} $

$ = \frac{1}{2}\{ \cos {30^o}\cos {23^o} - \sin {30^o}\sin {23^o}\} $

$ = \frac{1}{2}\,\cos \,({30^o} + {23^o}) $

$= \frac{1}{2}\,\cos \,{53^o}.$

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