Home
Class 12
MATHS
Prove that cos. (2pi)/(7). Cos. (4pi)/(...

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

Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRIC RATIONS, TRANSFORMATIONS

    SRISIRI PUBLICATION|Exercise VSAQ|51 Videos

  • TRIGONOMETRIC RATIONS, TRANSFORMATIONS

    SRISIRI PUBLICATION|Exercise LAQ|64 Videos

  • TRIGONOMETRIC EQUATIONS

    SRISIRI PUBLICATION|Exercise SPQ|8 Videos

Similar Questions

Explore conceptually related problems

"cos" (2pi)/(7)+"cos" (4pi)/(7)+"cos"(6pi)/(7)=

If A is not an integral multiple of (pi) , prove that cos A cos 2A cos 4A cos 8A =(sin 16A)/(16 sin A) Hence deduce that cos. (2pi)/(15). Cos. (4pi)/(15) .cos. (8pi)/(18). Cos. (16pi)/(15)=(1)/(16)

Prove that cos. (pi)/(11). cos . (2 pi)/(11). cos . (3 pi)/(11) cos. (4 pi)/(11). cos . (5 pi)/(11)=(1)/(32)

cos (pi/7) cos ((2pi)/(7) ) cos ( (4pi )/(7) ) =

Show that cos Acos ((pi)/(3)+A)cos ((pi)/(3)-A)=(1)/(4) cos 3A Hence deduce that cos.(pi)/(9) cos. (2pi)/(9)cos. (4pi)/(9)=(1)/(8)

cos. (pi)/(7) + cos. (2pi)/(7) + cos. (3pi)/(7) + cos. (4pi)/(7) + cos. (5pi)/(7) + cos. (6pi)/(7)=

Show that (1+ cos. (pi)/(8))(1+cos. (3pi)/(8))(1+ cos. (5pi)/(8))(1+ cos .(7pi)/(8))=(1)/(8)

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

In Delta ABC , prove that cos. (A)/(2)+cos. (B)/(2) - cos .(C)/(2)=4cos .(pi+A)/(4) cos. (pi+B)/(4) cos. (pi-C)/(4)

SRISIRI PUBLICATION-TRIGONOMETRIC RATIONS, TRANSFORMATIONS-LAQ
  1. Prove that cos. (2pi)/(7). Cos. (4pi)/(7). Cos. (8pi)/(7)=(1)/(8)

    Text Solution

    |

  2. If A+B+C= 180^(@), then show that sin 2A+ sin 2B+ sin 2C =4 sin A sin...

    Text Solution

    |

  3. If A, B, C are angles of a triangle, then S. T sin 2A -sin 2B + sin...

    Text Solution

    |

  4. If A, B, C are angles of a triangle , prove that cos 2A - cos 2B + ...

    Text Solution

    |

  5. If A , B , C are angles in a triangle , then prove that sin A + sin ...

    Text Solution

    |

  6. IF A,B,C are angles in the triangle, then prove that cosA+cosB-cosC=...

    Text Solution

    |

  7. If A, B , C are angles in a triangle, then the sin ^(2)A+sin ^(2)B - s...

    Text Solution

    |

  8. If A+B+ C =pi, then prove that cos ^(2) (A/2)+ cos ^(2) (B/2) +cos ^(2...

    Text Solution

    |

  9. If A, B , C are angles of a triangle, then P. T sin ^(2) . (A)/(2)+ si...

    Text Solution

    |

  10. In triangle ABC, prove that cos .(A)/(2)+cos.(B)/(2)+cos. (C)/(2) =4 c...

    Text Solution

    |

  11. If A, B, C are the angles in a triangle then prove that sin .(A)/(2)+...

    Text Solution

    |

  12. If A+B+C=(pi)/(2), then prove that cos 2A + cos 2B + cos 2C=1+4 sin A ...

    Text Solution

    |

  13. If A+B+C=(pi)/(2), then prove that sin ^(2) A+ sin ^(2) B + sin ^(2) C...

    Text Solution

    |

  14. If A+B+C=(3pi)/(2), prove that cos 2A+ cos 2B+ cos 2C=1-4 sin A sin B ...

    Text Solution

    |

  15. If A+B+C=(3pi)/(2), prove that cos ^(2)A+ cos ^(2) B- cos ^(2)C=-2 cos...

    Text Solution

    |

  16. If A+B+C=0, then prove that cos ^(2)A+ cos ^(2) B + cos ^(2) C =1+2 co...

    Text Solution

    |

  17. If A+B+C = 2S , then P.T cos(S-A)+cos(S-B)+cos(S-C)+cosS=4cos.(A)/(...

    Text Solution

    |

  18. If A+B+C+D=360^(@), the prove that cos 2A + cos 2B + cos 2C + cos 2D =...

    Text Solution

    |

  19. Find the value of 2(sin^(6)theta+cos^(6)theta)-3(sin^(4)theta+cos^(4)t...

    Text Solution

    |

  20. Prove that (1+cot theta -"cosec" theta ) (1+ tan theta + sec theta )=2...

    Text Solution

    |

  21. If (2 sin theta )/(1+ cos theta + sin theta )=x, find the value of (1...

    Text Solution

    |