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If z^7+1 =0 then cos(pi/7) cos((3pi)/7) ...

If `z^7+1 =0` then `cos(pi/7) cos((3pi)/7) cos((5pi)/7)` is (A) `1/8` (B) `-1/8` (C) `1/(2sqrt2)` (D) `1/2`

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A DAS GUPTA-COMPLEX NUMBERS-EXERCISE
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  2. If z=costheta+isintheta is a root of the equation a0z^n+a2z^(n-2)++a(n...

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  3. If z^7+1 =0 then cos(pi/7) cos((3pi)/7) cos((5pi)/7) is (A) 1/8 ...

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