MCQ
$\sqrt {2 + \sqrt {2 + 2\cos 4\theta } } = $
  • A
    $\cos \theta $
  • B
    $\sin \theta $
  • $2\cos \theta $
  • D
    $2\sin \theta $

Answer

Correct option: C.
$2\cos \theta $
c
(c) $\sqrt {2 + \sqrt {2 + 2\cos 4\theta } } $

$=\sqrt {2 + \sqrt {2.2{{\cos }^2}2\theta } } $

$ = \sqrt {2 + 2\cos 2\theta }$

$= \sqrt {4{{\cos }^2}\theta } $

$= 2\cos \theta $.

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