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Prove that: 2cospi/(13)cos(9pi)/(13)+cos...

Prove that: `2cos``pi/(13)``cos``(9pi)/(13)``+cos``(3pi)/(13)``+cos``(5pi)/(13)=0`

A

0

B

`-1`

C

1

D

2

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AAKASH INSTITUTE ENGLISH-TRIGNOMETRIC FUNCTIONS -Assignment section-A (Objective Type Questions (One option is correct))
  1. In a triangleABC, if sinA - cosB = cos C, then the measured of angleB ...

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  2. The value of "cos"1^(@)."cos"2^(@)."cos"3^(@)......."cos"179^(@) is

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  3. Prove that: 2cospi/(13)cos(9pi)/(13)+cos(3pi)/(13)+cos(5pi)/(13)=0

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  4. If sintheta +costheta =1, then the value of sin2theta is equal to

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  5. If "tan"A=1/(2),"tan"B=1/(3), then "tan"(2A+B) is equal to

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  6. The minute hand of a watch is 3 cm long. How far does its tip move in ...

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  7. If sintheta=(-4)/(5) and theta lies in third quadrant, then the value...

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  8. The value of tan75^(@) =

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  9. If omega is a non-real cube root of unity and n is not a multiple o...

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  10. The value of 2sinA cos^(3)A -2sin^(3)A cosA is

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  11. If tanalpha=(sqrt(3)+1)/(sqrt(3)-1), then the expression cos 2alpha +(...

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  12. If sin^2 theta=1/4 , then the value of theta is

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  13. The solution of the equation cos^2theta+sintheta+1=0 lies in the inter...

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  14. The general solution of tan3x=1 is

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  15. If sin theta =sqrt(3) cos theta, -pi lt theta lt 0, then the value of ...

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  16. Number of solution of the equation tanx+secx=2cosx lying in the interv...

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  17. If the lengths of the sides of a triangle are 3, 5, 7, then its larges...

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  18. The value of sin^2 75^0-sin^2 15^0 is a. 1//2 b. sqrt(3)//2 c. 1 d. 0

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  19. If a cosA=b cosB, then triangleABC is

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  20. If a=16, b=24 and c=20, then the value of cos(B/2) is

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