A) 0
B) 1
C) \[-1\]
D) \[-\frac{1}{2}\]
Correct Answer: A
Solution :
\[2\cos \frac{52{}^\circ +68{}^\circ }{2}.\cos \frac{68{}^\circ -52{}^\circ }{2}+\cos \,\,(180{}^\circ -8{}^\circ )\] \[\,\,=2\cos 60{}^\circ \cdot \cos 8{}^\circ -\cos 8{}^\circ \] \[\,\,\,=2\times \frac{1}{2}\times \cos 8{}^\circ -\cos 8{}^\circ =0\]You need to login to perform this action.
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