Home
Class 11
MATHS
3 cos 72 ^(@) -4 sin ^(3) 18^(@) = cos 3...

`3 cos 72 ^(@) -4 sin ^(3) 18^(@) = cos 36 ^(@).`

Text Solution

AI Generated Solution

Promotional Banner

Topper's Solved these Questions

  • COMPOUND AND MULTIPLE ANGLES

    ICSE|Exercise CHEPTER TEST |23 Videos

  • COMPOUND AND MULTIPLE ANGLES

    ICSE|Exercise EXERCISE 5 (C ) |30 Videos

  • COMPLEX NUMBERS

    ICSE|Exercise Chapter Test|25 Videos

  • CONIC SECTIONS

    ICSE|Exercise Multiple Choice Questions |33 Videos

Similar Questions

Explore conceptually related problems

4 cos 12 ^(@) cos 48^(@) cos 72^(@) = cos 36 ^(@)

cos ^(2) 36^(@) + sin ^(2) 18^(@) = (3)/(4).

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

cos 12 ^(@) cos 24 ^(@) cos 36 ^(@) cos 48^(@) cos 72^(@) cos 84^(@) = (1)/(2 ^(6))

Prove that sin 36 ^(@) + cos 36 ^(@) = sqrt2 cos 9^(@).

i) Prove that: cos^(3)2A+3cos2A = 4(cos^(6)A-sin^(6)A) ii) Prove that: 4(cos^(3)10^(@) + sin^(3)20^(@)) = 3(cos10^(@)+sin20^(@))

Prove that cos 36^(@) cos 72^(@) cos 108^(@) cos 144^(@)=1//16 .

Prove that : cos 36 ^(@) - sin 18^(@) = (1)/(2).

Prove that: (i) cos55^(@)sin 35^(@)+sin 55^(@)cos 35^(@)=1 (ii) (tan 72^(@))/(cot 18^(@))-(cot 72^(@))/(tan18^(@))=0 (iii) sec70^(@)sin 20^(@)+cosec 70^(@)cos 20^(@)=2

The value of (sin 1^(@) +sin 3^(@) + sin 5^(@) +sin 7^(@))/(cos 1^(@)*cos 2^(@)sin 4^(@)) is __________

ICSE-COMPOUND AND MULTIPLE ANGLES -EXERCISE 5 (D)
  1. Prove that : cos 36 ^(@) - sin 18^(@) = (1)/(2).

    Text Solution

    |

  2. cos ^(2) 36^(@) + sin ^(2) 18^(@) = (3)/(4).

    Text Solution

    |

  3. 3 cos 72 ^(@) -4 sin ^(3) 18^(@) = cos 36 ^(@).

    Text Solution

    |

  4. cos ^(2) 48^(@) - sin ^(2) 12 ^(@) = (sqrt5+1)/(8).

    Text Solution

    |

  5. Prove that sin "" (1)/(10) pi cos ""(1)/(5) pi = (1)/(4).

    Text Solution

    |

  6. sec 72 ^(@) - sec 36^(@) = 2.

    Text Solution

    |

  7. sin ^(2) 24 ^(@) - sin ^(2) 6^(@) = (sqrt5 -1)/(8).

    Text Solution

    |

  8. sin 12 ^(@) sin 48^(@) sin 54 ^(@) = (1)/(8).

    Text Solution

    |

  9. Prove that 4 cos 6^(@) cos 42 ^(@) cos 66^(@) cos 78^(@) = (1)/(4).

    Text Solution

    |

  10. sin "" (pi)/(5) sin "" (2pi)/(5) sin ""(4pi)/(5) sin""(3pi)/(5) = (5)/...

    Text Solution

    |

  11. Prove that cos "" (2pi)/(15) cos "" (4pi)/(15) cos "" (8pi)/(15) cos "...

    Text Solution

    |

  12. cos ^(2) ""(pi)/(10) + cos ^(2) ""(2pi)/(5) + cos^(2) ""(3pi)/(5) + co...

    Text Solution

    |

  13. tan 6 ^(@) tan 42 ^(@) tan 66 ^(@) tan 78^(@) =1

    Text Solution

    |

  14. cos alpha cos 2 alpha cos 4 alpha cos 8 alpha = (1)/(16), if alpha =...

    Text Solution

    |

  15. cos 12 ^(@) cos 24 ^(@) cos 36 ^(@) cos 48^(@) cos 72^(@) cos 84^(@) =...

    Text Solution

    |

  16. If theta = (pi)/(2 ^(n) +1) prove that 2 ^(n) cos theta cos 2 theta c...

    Text Solution

    |

  17. If tan "" (x-y)/( 2 ), tan z, tan "" (x + y)/( 2) are in G.P. then sho...

    Text Solution

    |

  18. If sin theta is G.M. of sin phi and cos phi, then prove that cos 2 th...

    Text Solution

    |

  19. If m tan (theta - 30^(@))= n tan (theta + 120^(@)), show that cos 2 th...

    Text Solution

    |

  20. If sin alpha = lamda sin (theta - alpha ) then prove that tan (alpha...

    Text Solution

    |