A) \[\sqrt{7}\]
B) \[-\sqrt{7}\]
C) 7
D) -7
Correct Answer: B
Solution :
\[\cos A=\frac{3}{4}\Rightarrow \sin A=\frac{\sqrt{7}}{4}\] L.H.S \[=16(\sin 3A-\sin 2A)\] \[=16\sin A(3-4{{\sin }^{2}}A-2\cos A)\] \[=16.\frac{\sqrt{7}}{4}\left( 3-4.\frac{7}{16}-2.\frac{3}{4} \right)=-\sqrt{7}\].
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