Home
Class 11
MATHS
2 cos ""pi/13 cos "" (9pi)/( 13) + cos "...

`2 cos ""pi/13 cos "" (9pi)/( 13) + cos "" (3pi)/(13) + cos " (5pi)/( 13) =0`

Promotional Banner

Topper's Solved these Questions

  • STRAIGHT LINE

    PATHFINDER|Exercise QUESTION BANK |25 Videos

  • TRIGONOMETRIC EQUATION

    PATHFINDER|Exercise QUESTION BANK|21 Videos

Similar Questions

Explore conceptually related problems

Prove that "cos" (3pi)/13 + "cos" (5pi)/13 - 2 "cos" (9pi)/13 "cos" (12pi)/13 = 0

cos(pi/14) + cos ((3pi)/14) + cos((5pi)/14) =

The value of cos ""pi/7 cos ""(2pi)/(7) cos ""(3pi)/(7) is-

Prove that, (1 + "cos" pi/8)(1 + "cos" (3pi)/8)(1 + "cos" (5pi)/8)(1 + "cos" (7pi)/8 ) = 1/8

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

The value of (1+ cos ""(pi)/(8))(1+cos""(3pi)/(8))(1+ cos ""(5pi)/(8)) (1+ cos "'(7pi)/(8)) is-

2 cos(pi/3 +A)=

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

The value of cos""(pi)/(15)cos""(2pi)/(15)cos""(4pi)/(15)cos""(8pi)/(15) is

"Show that : " "cos" pi/11 +"cos"(3pi)/11+ "cos" (5pi)/11+ "cos" (7pi)/11+"cos" (9pi)/11 =1/2 .

PATHFINDER-TRANSFORMATION FORMULAE-QUESTION BANK
  1. Prove that (sinA+sinB)/(sinA-sinB)=tan((A+B)/2)cot((A-B)/2)

    Text Solution

    |

  2. Prove that (sinA+sin3A)/(cosA+cos3A)=tan2A.

    Text Solution

    |

  3. Evaluate:sin75^@ cdot cot15^@

    Text Solution

    |

  4. Prove that (sinA+sinB)/(cosA+cosB)=tan((A+B)/2)

    Text Solution

    |

  5. Prove that2"sin"(5pi)/(12)"cos"(pi)/(12)=(sqrt3+2)/2

    Text Solution

    |

  6. If sin(theta+alpha)/(cos(theta-alpha))=(1-m)/(1+m) Prove that tan(pi/4...

    Text Solution

    |

  7. If cosecA+secA=cosecB+secB Prove that tanAtanB=cot((A+B)/2).

    Text Solution

    |

  8. Prove that (sin(theta+phi)-2sintheta+sin(theta-phi))/(cos(theta+phi)-2...

    Text Solution

    |

  9. Show thatsinalpha+sinbeta+singamma-sin(alpha+beta+gamma)=4sin ((alpha+...

    Text Solution

    |

  10. Prove that cos10^@cos30^@cos50^@cos70^@=3/(16).

    Text Solution

    |

  11. Prove that sin20^@sin40^@sin80^@=sqrt3/8

    Text Solution

    |

  12. Prove thatsin10^@sin50^@sin60^@sin70^@=sqrt3/(16)

    Text Solution

    |

  13. Prove that tan20^@tan30^@tan40^@tan80^@=1

    Text Solution

    |

  14. Prove that (sin5A-sin7A+sin8A-sin4A)/(cos4A+cos7A-cos5A-cos8A)=cot6A

    Text Solution

    |

  15. Prove that (cosalpha+cosbeta)^2+(sinalpha+sinbeta)^2=4cos^2((alpha-bet...

    Text Solution

    |

  16. Prove that sinalpha+sin(alpha+(2pi)/3)+sin(alpha+(4pi)/3)=0.

    Text Solution

    |

  17. 2 cos ""pi/13 cos "" (9pi)/( 13) + cos "" (3pi)/(13) + cos " (5pi)/( 1...

    Text Solution

    |

  18. Show that tan20^@tan40^@tan80^@=sqrt3

    Text Solution

    |

  19. If cosA+cosB=1/2and sinA+sinB=1/4Prove that tan((A+B)/2)=1/2

    Text Solution

    |

  20. If sin2A=lamdasin2B.Prove that tan(A+B)/(tan(A-B))=(lamda+1)/(lamda-1)

    Text Solution

    |