Home
Class 11
MATHS
Prove that: cos(pi/5)cos((2pi)/5)cos((4p...

Prove that: `cos(pi/5)cos((2pi)/5)cos((4pi)/5)cos((8pi)/5)=(-1)/16`

Text Solution

AI Generated Solution

Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRIC RATIOS OF COMPOUND ANGLES

    RD SHARMA ENGLISH|Exercise All Questions|149 Videos

Similar Questions

Explore conceptually related problems

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

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

Show that cos(pi/65)cos((2pi)/65)cos((4pi)/65)cos((8pi)/65)cos((16pi)/65)cos((32pi)/65)=1/64

Prove: cos(pi/15)cos((2pi)/15)cos((3pi)/15)cos((4pi)/15)cos((5pi)/15)cos((6pi)/15)cos((7pi)/15) = 1/2^7

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

3.Prove that (i) "cos((2pi)/7)*cos((4pi)/7)*cos((8pi)/7)=1/8

Prove that : cos(pi/7)cos((2pi)/7) cos((3pi)/7)=1/8

Prove that cos(2pi)/(15)cos(4pi)/(15)cos(8pi)/(15)cos(14pi)/(15)=1/(16)

cospi/5+cos(2pi)/5+cos(6pi)/5+cos(7pi)/5=0

Prove that cos((2pi)/(15))cos((4pi)/(15))cos((8pi)/(15))cos((16pi)/(15))=1/(16)

RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS OF MULTIPLE AND SUBMULTIPLE ANGLES-All Questions
  1. If sintheta=4/5 and 0ltthetaltpi/ 2, find the value of sin4theta

    Text Solution

    |

  2. Prove that: \ cos7^0cos 14^0cos 28^0cos 56^0=(sin 68^0)/(16cos83^0)

    Text Solution

    |

  3. Prove that: cos(pi/5)cos((2pi)/5)cos((4pi)/5)cos((8pi)/5)=(-1)/16

    Text Solution

    |

  4. cos(pi/65)cos((2pi)/65)cos((4pi)/65)cos((8pi)/65)cos((16pi)/65)cos((32...

    Text Solution

    |

  5. If 2\ t a nalpha=3t a nbeta, prove that tan(alpha-beta)=(sin2beta)/(5...

    Text Solution

    |

  6. sinalpha+sinbeta=a ,cosalpha+cosbeta=b=>sin(alpha+beta)

    Text Solution

    |

  7. If sinalpha+sinbeta=a and cosalpha+cosbeta=b prove that: cos(alpha-bet...

    Text Solution

    |

  8. If costheta=(cosalpha+cosbeta)/(1+cosalphacosbeta),\ prove that tanth...

    Text Solution

    |

  9. If sec(theta+alpha)+sec(theta-alpha)=2\ s e ctheta, prove that costhet...

    Text Solution

    |

  10. If cos alpha=4/5 and cos beta =5/13, prove that cos (alpha-beta)/2=28/...

    Text Solution

    |

  11. Prove that: 8cos^3pi/9-\ 6cospi/9=1.

    Text Solution

    |

  12. Prove that: 108sinpi/(18)-144sin^3pi/(18)=18

    Text Solution

    |

  13. Prove that cos6A=32cos^6A-48cos^4A+18cos^2A-1

    Text Solution

    |

  14. Prove that : cos Acos(60-A)cos(60+A)=1/4cos3A

    Text Solution

    |

  15. Prove that: "s i n A s i n"(60-"A")sin(60+"A")=1/4sin3"A"dot

    Text Solution

    |

  16. Prove that: "sin"20^0"sin"40^0"sin"60^0"sin"80^0=3/(16)

    Text Solution

    |

  17. prove sin(5theta) = 16sin^5(theta)-20sin^3(theta)+5sin(theta)

    Text Solution

    |

  18. Prove that 4(cos ^(3) 10^(@) + sin ^(3) 20^(@)) = 3 ( cos 10^(@) + sin...

    Text Solution

    |

  19. Prove the following identity: cos^3thetasin3theta+sin^3thetacos3theta=...

    Text Solution

    |

  20. Prove the following identity: \ t a nthetat a n(theta+60^0)+t a ntheta...

    Text Solution

    |