Home
Class 11
MATHS
Show that CosA=(Cos3A)/(2Cos2A-1). Hence...

Show that `CosA=(Cos3A)/(2Cos2A-1)`. Hence find the value of `Cos15^(@)`

Text Solution

Verified by Experts

The correct Answer is:
`(sqrt(3)+1)/(2sqrt(2))`
Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRIC RATIOS UPTO TRANSFORMATIONS

    VIKRAM PUBLICATION ( ANDHRA PUBLICATION)|Exercise EXERCISE - 6(E)|20 Videos

  • TRIGONOMETRIC RATIOS UPTO TRANSFORMATIONS

    VIKRAM PUBLICATION ( ANDHRA PUBLICATION)|Exercise EXERCISE - 6(F)|20 Videos

  • TRIGONOMETRIC RATIOS UPTO TRANSFORMATIONS

    VIKRAM PUBLICATION ( ANDHRA PUBLICATION)|Exercise EXERCISE - 6(C)|40 Videos

  • TRIGONOMETRIC EQUATIONS

    VIKRAM PUBLICATION ( ANDHRA PUBLICATION)|Exercise SOLVED PROBLEMS |18 Videos

Similar Questions

Explore conceptually related problems

Show that sin A= (sin 3A) /(1+2 cos 2A) . Hence find the value of sin 15^(@).

Find the values of cos(67""1/2)^(@)

Find the values of cos22""1_(@)/2

Find the value of Sin 75^@ - Cos 15^@

S.T tan alpha =(sin 2 alpha )/(1+cos 2 alpha ) . Hence find the value of tan 15^(@) and tan 22 1//2^(@)

Find the value of cos^(2)45^(@)-sin^(2)15^(@)

VIKRAM PUBLICATION ( ANDHRA PUBLICATION)-TRIGONOMETRIC RATIOS UPTO TRANSFORMATIONS-EXERCISE - 6(D)
  1. If 90^(@) lt theta lt 180^(@) , cos theta =-12//13 , then sin 2 thet...

    Text Solution

    |

  2. (Cos^(3)theta-Cos3theta)/(Costheta)+(Sin^(3)theta+Sin3theta)/(Sintheta...

    Text Solution

    |

  3. Show that CosA=(Cos3A)/(2Cos2A-1). Hence find the value of Cos15^(@)

    Text Solution

    |

  4. Show that sin A= (sin 3A) /(1+2 cos 2A). Hence find the value of sin 1...

    Text Solution

    |

  5. Prove that tanalpha=(sigmatauv2alpha)/(1+chiosigma2alpha) and hence de...

    Text Solution

    |

  6. Show that 1/(sin 10^(@)) - (sqrt(3))/(cos 10^(@)) = 4.

    Text Solution

    |

  7. Prove that sqrt(3)"cosec"20^(@)-"sec"20^(@) =4.

    Text Solution

    |

  8. tan9^(@)-tan27^(@)-tan63^(@)+tan81^(@)=

    Text Solution

    |

  9. In a Delta ABC, If tan .(A)/(2)=(5)/(6) and tan .(B)/(2) =(20)/(37), ...

    Text Solution

    |

  10. If cos theta =(5)/(13) and 270 ^(@) lt theta lt 360^(@), evaluate sin ...

    Text Solution

    |

  11. If 180^(@) lt theta lt 270^(@) and sintheta=(-4)/5 calculate sin[theta...

    Text Solution

    |

  12. cos^(2) pi/8 + cos^(2) 3pi/8 + cos^(2) 5pi/8 + cos^(2) 7pi/8 =2 అని చూ...

    Text Solution

    |

  13. Show that cos^4""pi/8+cos^4""(3pi)/8+cos^4""(5pi)/8+cos^4""(7pi)/8=3/2

    Text Solution

    |

  14. tan x + tan (x +pi/3) + tan (x +2pi/3) =3 అయితే , tan 3x =1 అని చూపండి...

    Text Solution

    |

  15. Show that sin""(pi)/5.sin""(2pi)/5.sin""(3pi)/5.sin""(4pi)/5=5/16.

    Text Solution

    |

  16. cos^(2)(pi/10) + cos^(2) (2pi/5)+ cos^(2)(3pi/5) + cos^(2)(9pi/10) = 2...

    Text Solution

    |

  17. Prove that (1+cos""pi/10)(1+cos""(3pi)/10)(1+cos""(7pi)/10)(1+cos""(9p...

    Text Solution

    |

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

    Text Solution

    |

  19. If cos alpha =(3)/(5) and cos beta =(5)/(13) and alpha, beta are acut...

    Text Solution

    |

  20. If cos alpha=3/5 and cos beta = 5/13 and alpha , beta are acute angles...

    Text Solution

    |