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cos""(2pi)/(15)cos""(4pi)/(15)cos""(8pi)...

`cos""(2pi)/(15)cos""(4pi)/(15)cos""(8pi)/(15)cos""(16pi)/(15)=(1)/(16)`

A

0

B

1

C

`-1`

D

`1//8`

Text Solution

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The correct Answer is:
D
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OBJECTIVE RD SHARMA-TRIGONOMETRIC RATIOS AND IDENTITIES-Exercise
  1. The value of sin""(pi)/(7)sin""(2pi)/(7)sin""(3pi)/(7), is

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  2. The value of sin""(2pi)/(7)+sin""(4pi)/(7)+sin""(8pi)/(7), is

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  3. cos""(2pi)/(15)cos""(4pi)/(15)cos""(8pi)/(15)cos""(16pi)/(15)=(1)/(16)

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  4. If sinA+cosA=m an sin^(3)A+cos^(3)A=n, then

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  5. If cosA+cosB=m and sinA+sinB=n then sin(A+B)=

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  6. If ltA lt(pi)/(6) and sinA+cosA=(sqrt7)/(2),"then" tan""(A)/(2)=

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  7. The value of cos""(pi)/(11)+cos""(3pi)/(11)+cos""(5pi)/(11)+cos""(7pi)...

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  8. If n=pi/(4alpha), then tanalpha tan 2alpha tan 3 alpha........tan(2n-1...

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  9. the value of tan9^@-tan2 7^@-tan6 3^@+tan8 1^@ is equal to

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  10. For x in R, tanx+1/2tan""(1)/(2^(2))tan""(x)/(2^(2))+...+(1)/(2^(n-1...

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  11. If (tan3A)/(tanA)=k, then (sin3A)/(sinA)=

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  12. If y=(sec^(2)theta-tantheta)/(sec^(2)theta+tantheta)'then

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  13. If cosA=tanB, cos B=tanC, cosC=tanA, then sin A is equal to

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  14. If A(1)A(2)A(3)A(4)A(5) be regular pentgon inscribed in anunit circle....

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  15. If tanalpha is equal to the integral solution of the inequality 4x^2-1...

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  16. If (x)/(cos theta)=(y)/(cos(theta-(2pi)/(2)))=(2)/(cos(theta+(2pi)/(3)...

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  17. If cos A=3/4 then the value of sin(A/2) sin((5A)/2) is

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  18. The minimum value of 9tan^2theta+4cot^2theta is

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  19. If x(1),x(2),x(3),...,x(n) are in A.P. whose common difference is alph...

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  20. If asin^2x+bcos^2x=c,bsin^2y+acos^2y=d and atanx=btany then a^2/b^2=.....

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