Question

Find the value of cos12° + cos84° + cos156° + cos132° .​

Answer 1

Answer:

cos12° + cos84° + cos156° + cos132° = -1/2.

✔️Hope it will be helpful.✔️

Answer 2

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$\boxed{Explained\:Answer}$

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cos132+cos12+cos156+cos84

=2cos72cos60+2cos120cos36

=2[(root5-1)/4]1/2+2(-1/2)(root5+1)/4

=-1/2