Home
Class 12
MATHS
cos(2pi/7)+cos(4pi/7)+cos(6pi/7)...

`cos(2pi/7)+cos(4pi/7)+cos(6pi/7)`

A

`1`

B

`-1`

C

`1//2`

D

`-1//2`

Text Solution

Verified by Experts

The correct Answer is:
D
Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRIC RATIOS AND IDENTITIES

    OBJECTIVE RD SHARMA|Exercise Chapter Test|60 Videos

  • TRIGONOMETRIC RATIOS AND IDENTITIES

    OBJECTIVE RD SHARMA|Exercise Section II - Assertion Reason Type|13 Videos

  • TRIGONOMETRIC EQUATIONS AND INEQUATIONS

    OBJECTIVE RD SHARMA|Exercise Chapter Test|60 Videos

Similar Questions

Explore conceptually related problems

Prove that cos((2pi)/7) cos((4pi)/7) cos((8pi)/7) =1/8

Prove that cos((2pi)/7)cos((4pi)/7)cos((8pi)/7)=1/8

prove that cos2(pi)/(7)+cos4(pi)/(7)+cos6(pi)/(7)=-(1)/(2)

Find the value of cos(2 pi)/(7)+cos(4 pi)/(7)+cos(6 pi)/(7)

Prove that 4cos((2pi)/7).cos(pi/7)-1=2cos((2pi)/7) .

Prove that: cos(pi)/(7)cos(2 pi)/(7)cos(4 pi)/(7)=-(1)/(8)

Find the value of (cos(2 pi))/(7)(cos(4 pi))/(7)(cos(6 pi))/(7)

The value of cos(2pi)/7cos(4pi)/7cos6/7pi is a. -1//2 b. \ 1//2 c. \ 1//4 d. 1//8

the value of (cos pi)/(7)cos(2(pi)/(7))cos(3(pi)/(7)) is

OBJECTIVE RD SHARMA-TRIGONOMETRIC RATIOS AND IDENTITIES-Exercise
  1. The value of cot36^(@)cot72^(@), is

    Text Solution

    |

  2. The value of cospi/7+cos(2pi)/7+cos(3pi)/7+cos(4pi)/7+cos(5pi)/7+cos(6...

    Text Solution

    |

  3. cos(2pi/7)+cos(4pi/7)+cos(6pi/7)

    Text Solution

    |

  4. The value of cos""(pi)/(9)cos""(2pi)/(9)cos""(3pi)/(9), is

    Text Solution

    |

  5. The value of cos""(pi)/(9)cos""(2pi)/(9)cos""(3pi)/(9)cos""(4pi)/(9), ...

    Text Solution

    |

  6. The vlaue of cosec^(2)""(pi)/(7)+cosec^(2)""(2pi)/(7)+cosec^(2)""(3pi)...

    Text Solution

    |

  7. sin1 2^(@)sin4 8^(@)sin5 4^(@)=

    Text Solution

    |

  8. the value of sin(pi/7)+sin((2pi)/7)+sin((3pi)/7) is

    Text Solution

    |

  9. cos^6pi/9-33tan^4pi/9+27tan^2pi/9 is equal to 0 (b) sqrt(3) (c) 3 ...

    Text Solution

    |

  10. (sin^2 3A)/(sin^2A)-(cos^2 3A)/(cos^2A)=

    Text Solution

    |

  11. If sinA=(336)/(625)where450^(@)ltAlt540^(@), then sin""(A)/(4)=

    Text Solution

    |

  12. If y=(tanx)/(tan3x), then

    Text Solution

    |

  13. The value of cot^(2)""(pi)/(7)+cot^(2)""(2pi)/(7)+cot^(2)""(3pi)/(7), ...

    Text Solution

    |

  14. The value of sin""(pi)/(7)sin""(2pi)/(7)sin""(3pi)/(7), is

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |