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If cos(pi/7), cos((3pi)/7), cos((5pi)/7)...

If `cos(pi/7), cos((3pi)/7), cos((5pi)/7)` are the roots of the equation `8x^3-4x^2-4x+1=0`
The value of `sec(pi/7)+sec((3pi)/7)+sec((5pi)/7)` is

A

2

B

4

C

8

D

none of thesee

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The correct Answer is:
B
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