If $A + B + C = \frac{{3\pi }}{2},$ then $\cos 2A + \cos 2B + \cos 2C = $
If $A + B + C = \frac{{3\pi }}{2},$ then $\cos 2A + \cos 2B + \cos 2C = $
- A
$1 - 4\cos A\,\cos B\,\cos C$
- B
$4\sin A\,\,\sin B\,\,\sin C$
- C
$1 + 2\cos A\,\cos B\,\cos C$
- D
$1 - 4\sin A\,\,\sin B\,\,\sin C$
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