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about to only mathematics

A

1

B

`1/8`

C

`1/4`

D

`1/2`

Text Solution

Verified by Experts

The correct Answer is:
B
We have,
`sin""(pi)/(18)sin""(5pi)/(18)sin""(7pi)/(18)`
`=cos""(8pi)/(18)sin""(5pi)/(18)sin""(7pi)/(18)`
`=cos""(pi)/(9)cos""(2pi)/(9)cos""(4pi)/(9)=(sin(2^(3)xx(n)/(9)))/(2^(3)sin""(pi)/(9))=1/8`
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OBJECTIVE RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS AND IDENTITIES-Section I - Solved Mcqs
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  2. Which of the following statements about tan10^(@) is true?

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  3. about to only mathematics

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  4. If tanalpha=sqrta where a is not a perfect square then which of the fo...

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  5. If sec2 theta=p+tan2 theta, then the value of sin^(2)theta in therms o...

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  6. The value of sinpi/n + sin(3pi)/n + sin(5pi)/n +………. to n terms is equ...

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

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  8. Find the value of sum(r=1)^(n-1)sin^(2)""(rpi)/(n).

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  9. If tan""(2pi)/(18),x andtan""(7pi)/(18) are in A.P. and tan""(2pi)/(18...

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  10. The Minimum value of 27^cosx +81^sinx is equal to

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  11. The value of tan alpha +2tan(2alpha)+4tan(4alpha)+...+2^(n-1)tan(2^(n...

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  12. If tantheta + tan(theta + pi/3) + tan(theta-pi/3)= Ktan3theta, then K ...

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  13. For 0ltxlt(pi)/(6), all the values of tan^(2)3x cos^(2)x-4tan3xsin2x+1...

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  14. In a cyclic quadrilateral ABCD, the value of 2+sum cos A cos B, is

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  15. If x+y+z=pi,,tan x tanz=2and tanytanz=18,then tan^(2)z=

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  16. Biggest among (sin1+cos1),(sqrt(sin1))+sqrt(cos1)),sqrt(1+sin2)and 1...

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  17. In a DeltaABC, if tanA+2tanB=0, then which one is correct?

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  18. Find the maximum value of 1+sin((pi)/(4)+theta) +2sin ((pi)/(4)-thet...

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  19. If y =4sin^(2)theta-cos2theta,then y lies in the interval

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  20. If x=cos^2theta+sin^4theta then for all real values of theta

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