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sum(r=1)^(8)[sin(2pir//9)+icos(2pir//9)]...

`sum_(r=1)^(8)[sin(2pir//9)+icos(2pir//9)]`=

A

-1

B

1

C

i

D

`-i`

Text Solution

Verified by Experts

The correct Answer is:
D
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AAKASH SERIES-DEMOIVRE'S THEOREM-PRACTICE EXERCISE
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  2. The continued product of all values of root(5)(4) is

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  3. sum(r=1)^(8)[sin(2pir//9)+icos(2pir//9)]=

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  4. The values of sum(m=1)^(10)[sin(2pim//11)-icos(2pim//11)] is

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  7. If cos alpha+cosbeta+cosgamma = 0 = sinalpha + sinbeta + singamma then...

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  8. If cosalpha+cosbeta+cosgamma=0=sinalpha+sinbeta+singamma then sin(2alp...

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  9. If cosalpha+cosbeta+cosgamma=0=sin alpha+sinbeta+singamma then cos^2al...

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  10. If cosalpha+coabeta+cosgamma=0=sinalpha+sinbeta+singamma then cos(alph...

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  11. If a=cisalpha,b=cisbeta,c=cisgamma, and a/b+b/c+c/a-1=0 then cos(alph...

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  12. If A+B+C= pi and cos A+cos B+cos C=0=sin A+sin B+sin C , then sin 3A+...

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  13. The cube roots of 1+I are

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  14. The values of (sqrt3+i)^(1//4) are

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  18. Solve x^9-x^5+x^4-1=0

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