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The value of prod(r=1)^(7)cos\ (pi r)/(1...

The value of `prod_(r=1)^(7)cos\ (pi r)/(15)` is

A

`(1)/(64)`

B

`(1)/(128)`

C

`(1)/(32)`

D

`(1)/(4)`

Text Solution

Verified by Experts

The correct Answer is:
B
the value of …………..
`cos.(pi)/(15)cos.(2pi)/(15)cos.(4pi)/(15)cos.(7pi)/(15)=(1)/(16)`
`cos.(3pi)/(15)cos.(6pi)/(15) = (1)/(4)`
`cos.(5pi)/(15) = (1)/(2)`
`implies` required value is `(1)/(128)`
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