$1 - 2{\sin ^2}\left( {\frac{\pi }{4} + \theta } \right) = $
$1 - 2{\sin ^2}\left( {\frac{\pi }{4} + \theta } \right) = $
- A
$\cos 2\theta $
- B
$ - \cos 2\theta $
- C
$\sin 2\theta $
- D
$ - \sin 2\theta $
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