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The value of sum(r=0)^(10)cos^3(rpi)/3 i...

The value of `sum_(r=0)^(10)cos^3(rpi)/3` is equal to `1/4` (b) `1/8` (c) `-1/4` (d) `-1/8`

A

`-(7)/(8)`

B

`-(9)/(8)`

C

`-(3)/(8)`

D

`-(1)/(8)`

Text Solution

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The correct Answer is:
D
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