Home
Class 11
MATHS
If cosalpha+cosbeta=0=s inalpha+s inbeta...

If `cosalpha+cosbeta=0=s inalpha+s inbeta,` then prove that `cos2alpha+cos2beta=-2cos(alpha+beta)dot`

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

If cosalpha+cosbeta=0=sinalpha+sinbeta , then prove that cos2alpha +cos2beta=-2cos(alpha +beta) .

If cosalpha+cosbeta=0=sinalpha+sinbeta , then prove that cos2alpha+cos2beta+2cos(alpha+beta)=0

Prove that |cosalpha-cosbeta|lt=|alpha-beta|

If cosalpha+cosbeta=0=sinalpha+sinbeta, then cos2alpha+cos2beta is equal to (a) -2"sin"(alpha+beta) (b) -2cos(alpha+beta) (c) 2"sin"(alpha+beta) (d) 2"cos"(alpha+beta)

If alpha+beta= 60^0 , prove that cos^2 alpha + cos^2 beta - cosalpha cos beta = 3/4 .

If cosalpha+cosbeta+cosgamma=0 , then prove that cos3alpha+cos3beta+cos3gamma=12cosalphacosbetacosgamma

If cos(alpha+beta)=0 then sin(alpha+2beta)=

If cos^2alpha-sin^2alpha=tan^2beta," then prove that "tan^2alpha=cos^2beta-sin^2beta .

If cos alpha+ cos beta =1/3 and sin alpha+sin beta=1/4 prove that cos[(alpha-beta)/2] =+-(5/24)

lf cos^2 alpha -sin^2 alpha = tan^2 beta , then show that tan^2 alpha = cos^2 beta-sin^2 beta .

RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS OF MULTIPLE AND SUBMULTIPLE ANGLES-All Questions
  1. If 2t a nalpha/2=tan(beta/2) , prove that cosalpha=(3+5cosbeta)/(5+3c...

    Text Solution

    |

  2. If acos2theta+bsin2theta= c, alpha and beta as its roots , then prove ...

    Text Solution

    |

  3. If cosalpha+cosbeta=0=s inalpha+s inbeta, then prove that cos2alpha+co...

    Text Solution

    |

  4. Prove that: 15sin(5pi)/(12)+15cos(5pi)/(12)-20sin^3(5pi)/(12)-20cos(5p...

    Text Solution

    |

  5. Prove that: sin(pi/5)sin( (2pi)/5)sin(3pi/5)sin(4pi/5)=5/(16)

    Text Solution

    |

  6. Find general solution of the trigonometric equation sin5theta =1

    Text Solution

    |

  7. Prove that: sin^4(pi/8)+sin^4((3pi)/8)+sin^4((5pi)/8)+sin^4((7pi)/8)=...

    Text Solution

    |

  8. Prove that: cos^4pi/8+cos^4(3pi)/8+cos^4(5pi)/8+cos^4(7pi)/8=3/2

    Text Solution

    |

  9. Prove that:tan6^0tan42^0tan66^0tan78^0=1.

    Text Solution

    |

  10. If tanalpha=(1-cosbeta)/(sinbeta),t h e n (a)tan3alpha=tan2beta (b) ...

    Text Solution

    |

  11. Prove that: sin36^0=(sqrt(10-2sqrt(5)))/4 .

    Text Solution

    |

  12. The value of (cos3theta)/(2cos2theta-1) is equal to (a) costheta (b) ...

    Text Solution

    |

  13. The value of cos^4theta+sin^4theta-6cos^2theta is (a) cos2theta (b) s...

    Text Solution

    |

  14. Prove that: sin(pi/10)+sin((13pi)/10)=-1/2

    Text Solution

    |

  15. If tan(pi//4+theta)+""tan(pi//4-theta)=lambdasec2theta,t h e nlambda= ...

    Text Solution

    |

  16. Prove that: (1+cos4x)/(cot x-tanx)=1/2sin4x

    Text Solution

    |

  17. Prove that: (cos7x-cos8x)/(1+2cos5x)=cos2x-cos3x

    Text Solution

    |

  18. To prove (cos5x+cos4x)/(1-2cos3x)=-cos2x-cosx

    Text Solution

    |

  19. If tantheta= t, then tan2theta+sec2theta is equal to (a) (1+t)...

    Text Solution

    |

  20. Prove that: "cot"pi/(24)=sqrt(2)+sqrt(3)+sqrt(4)+sqrt(6)

    Text Solution

    |