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sum (k =1) ^(3) cos ^(2) (2k -1) pi/12 i...

`sum _(k =1) ^(3) cos ^(2) (2k -1) pi/12` is equal to

A

0

B

`1/2`

C

`-1/2`

D

`3/2`

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The correct Answer is:
D
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