Home
Class 11
MATHS
If costheta=4/5 and theta is acute, find...

If `costheta=4/5 and theta` is acute, find the `tan2theta`

Text Solution

Verified by Experts

Since `costheta=4/5`
So,
`tantheta=−3/4` `-ve` as `theta` is acute
we know
`tan2theta=(2tantheta)/(1−tan^2theta)`
...
Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRIC RATIOS OF COMPOUND ANGLES

    RD SHARMA|Exercise Solved Examples And Exercises|149 Videos

Similar Questions

Explore conceptually related problems

If sin theta =(3)/(5) and theta is acute, then find the value of (tan theta - 2 cos theta )/(3sin theta+sec theta ) .

If tan theta+cot theta=2 and theta is acute, then the value of tan^100 theta +cot^100 theta is equal to: यदि tan theta+cot theta=2 and theta is acute, तो tan^100 theta +cot^100 theta का मान ज्ञात करें जहाँ theta न्यून कोण है

If sin theta=costheta, theta is an acute angel, then tan theta= ….

If tan theta = 3//4 and theta is acute, then what is the value of sintheta ?

If costheta= (4)/(5) then find the value of (sinthetacostheta+tan^(2)theta) .

If tan theta+sec theta=3 and theta is acute angle,find the value of 5sin theta.

If tan theta = 3//4 and theta acute, then cosec theta is equal to

If sin^(2)theta+2cos^(2)theta+3sin^(2)theta+4cos^(2)theta+......+40 terms =405 where theta is acute,then find the value of tan theta

If costheta=3//7,and theta lies in the fourth quadrant, evaluate : sin(theta//2),cos(theta//2),tan(theta//2).

If sin5 theta=cos4 theta, whre 5 theta and 4 theta are acute angles,find the value of theta .

RD SHARMA-TRIGONOMETRIC RATIOS OF MULTIPLE AND SUBMULTIPLE ANGLES-Solved Examples And Exercises
  1. If sinx=(sqrt(5))/3a n d\ x lies in IInd quadrant, find the values of ...

    Text Solution

    |

  2. Prove that 1+cos^2 2x=2(cos^4x+sin^4x)

    Text Solution

    |

  3. If costheta=4/5 and theta is acute, find the tan2theta

    Text Solution

    |

  4. If sinx=4/5 and 0ltxltpi/ 2, find the value of sin4x

    Text Solution

    |

  5. Prove that: \ cos7^0cos 14^0cos 28^0cos 56^0=(s in 68^0)/(16cos83^0)

    Text Solution

    |

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

    Text Solution

    |

  7. cos((2pi)/65)cos((4pi)/65)cos((8pi)/65)cos((16pi)/65)=1/16

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

  13. If cos alpha=4/5 and cos beta =5/13, prove that cos (alpha-beta)=56/65

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |

  16. Prove that cos6x=32cos^6x-48cos^4x+18cos^2x-1

    Text Solution

    |

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

    Text Solution

    |

  18. Prove that: sin A sin(60-A)sin(60+A)=1/4sin3Adot

    Text Solution

    |

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

    Text Solution

    |

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

    Text Solution

    |