Home
Class 12
MATHS
"sin"^(2)(pi)/(8)+"sin"^(2)(3pi)/(8) +"s...

`"sin"^(2)(pi)/(8)+"sin"^(2)(3pi)/(8) +"sin"^(2)(5pi)/(8)+"sin"^(2)(7pi)/(8)=`_________

Text Solution

Verified by Experts

The correct Answer is:
`2.00`
Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRICAL IDENTITIES AND EQUATIONS

    MCGROW HILL PUBLICATION|Exercise Questions from Previous Years. AIEEE/JEE Main Papers|48 Videos
  • TRIGONOMETRICAL IDENTITIES AND EQUATIONS

    MCGROW HILL PUBLICATION|Exercise Questions from Previous Years. B-Architecture Entrance Examination Papers|20 Videos
  • TRIGONOMETRICAL IDENTITIES AND EQUATIONS

    MCGROW HILL PUBLICATION|Exercise EXERCISE (LEVEL 2 Single Correct Answer Type Questions)|30 Videos
  • THE DIMENSIONAL GEOMETRY

    MCGROW HILL PUBLICATION|Exercise QUESTIONS FROM PREVIOUS YEARS. B-ARCHITECTURE ENTRANCE EXAMINATION PAPERS|25 Videos
  • VECTOR ALGEBRA

    MCGROW HILL PUBLICATION|Exercise QUESTIONS FROM PREVIOUS YEARS. B-ARCHITECTURE ENTRANCE EXAMINATION PAPERS|20 Videos

Similar Questions

Explore conceptually related problems

sin^(2)(pi)/(4)+sin^(2)(3 pi)/(4)+sin^(2)(5 pi)/(4)+sin^(2)(7 pi)/(4)=2

(cos^(2)pi)/(8)+(sin^(2)(3 pi))/(8)+(sin^(2)(5 pi))/(8_(sin)^(2))(7 pi)/(8)=2

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

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

2sin((pi)/8)sin((2pi)/8)sin((3pi)/8)sin((5pi)/8)sin((6pi)/8)sin((7pi)/8) = ?

Prove that "sin"(pi)/(14)"sin"(3pi)/(14)"sin"(5pi)/(14)"sin"(7pi)/(14)=(1)/(8)

Value of the expression 2[sin^(8)[(pi)/(16)]+sin^(8)[(3 pi)/(16)]+sin^(8)[(5 pi)/(16)] + sin^(8)[(7 pi)/(16)]]

tan""(pi)/(8)tan""(pi)/(12)tan""(3pi)/(8)tan""(5pi)/(12)-sin^(2)""(pi)/(6)=?

To find the sum sin^(2) ""(2pi)/(7) + sin^(2)""(4pi)/(7) +sin^(2)""(8pi)/(7) , we follow the following method. Put 7theta = 2npi , where n is any integer. Then " " sin 4 theta = sin( 2npi - 3theta) = - sin 3theta This means that sin theta takes the values 0, pm sin (2pi//7), pmsin(2pi//7), pm sin(4pi//7), and pm sin (8pi//7) . From Eq. (i), we now get " " 2 sin 2 theta cos 2theta = 4 sin^(3) theta - 3 sin theta or 4 sin theta cos theta (1-2 sin^(2) theta)= sin theta ( 4sin ^(2) theta -3) Rejecting the value sin theta =0 , we get " " 4 cos theta (1-2 sin^(2) theta ) = 4 sin ^(2) theta - 3 or 16 cos^(2) theta (1-2 sin^(2) theta)^(2) = ( 4sin ^(2) theta -3)^(2) or 16(1-sin^(2) theta) (1-4 sin^(2) theta + 4 sin ^(4) theta) " " = 16 sin ^(4) theta - 24 sin ^(2) theta +9 or " " 64 sin^(6) theta - 112 sin^(4) theta - 56 sin^(2) theta -7 =0 This is cubic in sin^(2) theta with the roots sin^(2)( 2pi//7), sin^(2) (4pi//7), and sin^(2)(8pi//7) . The sum of these roots is " " sin^(2)""(2pi)/(7) + sin^(2)""(4pi)/(7) + sin ^(2)""(8pi)/(7) = (112)/(64) = (7)/(4) . The value of (tan^(2)""(pi)/(7) + tan^(2)""(2pi)/(7) + tan^(2)""(3pi)/(7))xx (cot^(2)""(pi)/(7) + cot^(2)""(2pi)/(7) + cot^(2)""(3pi)/(7)) is

MCGROW HILL PUBLICATION-TRIGONOMETRICAL IDENTITIES AND EQUATIONS -EXERCISE (Numerical Answer Type Questions)
  1. If sin^(2)theta=(x^(2)+y^(2)+1)/(2x), then x =

    Text Solution

    |

  2. If a=b cos (2pi//3)=c cos(4pi//3), then ab+bc+ca is equal to

    Text Solution

    |

  3. "sin"^(2)(pi)/(8)+"sin"^(2)(3pi)/(8) +"sin"^(2)(5pi)/(8)+"sin"^(2)(7pi...

    Text Solution

    |

  4. If tan theta+cot theta=4, then tan^(4) theta+cot^(4) theta=

    Text Solution

    |

  5. Suppose 0 lt theta lt pi//2. If a sin^(3)theta+b cos^(3) theta=sin the...

    Text Solution

    |

  6. Let alpha=pi//10, then sin alpha sin (3alpha)=

    Text Solution

    |

  7. Let theta=pi//5, then 4|cos theta cos (2 theta) cos(4 theta) cos (8 th...

    Text Solution

    |

  8. Let theta=pi//6, and a=(1+cos theta)(1+cos 2theta)(1+cos 4 theta) (1+c...

    Text Solution

    |

  9. If 0 lt a lt 1, then log(a)(tan 1^(@))+log(a)(tan 2^(@))+… + log(a)(ta...

    Text Solution

    |

  10. 4 sin((pi)/(18))sin((5pi)/(18))sin((7pi)/(18))=

    Text Solution

    |

  11. If cot (theta-alpha) cot(theta-beta)=cot^(2) theta, then 2(1+cot(2the...

    Text Solution

    |

  12. If alpha=(pi)/(28), and a=(sin alpha)/(cos(3alpha))+(sin (3alpha))/(c...

    Text Solution

    |

  13. Let alpha=pi//12 , and E=(1+cos alpha)(1+cos(3alpha))(1+cos(5alpha))(1...

    Text Solution

    |

  14. Suppose f(theta)=cos theta cos(2theta) cos(2^(2) theta)-cos(2^(n) t...

    Text Solution

    |

  15. For theta in R, let f(theta)=cos^(2)theta+cos^(2)(theta+pi//6)+sin...

    Text Solution

    |

  16. Let a(n)=sum(k=1)^(n)tan^(-1)((2^(k))/(2+4^(k))), then tan(a(oo)-a(2))...

    Text Solution

    |

  17. If (sin^(2)x)/(1+sin^(2)x)+(cos^(2)x)/(1+cos^(2)x)=2+(k)/(cos(4x)-17) ...

    Text Solution

    |

  18. (tan 10^(@)+tan 70^(@)-tan50^(@))^(2)= .

    Text Solution

    |

  19. tan^(6)((pi)/(9))-33 tan^(4)((pi)/(9))+27tan^(2)((pi)/(9))= .

    Text Solution

    |

  20. Let f(x)=cos^(2)((pi)/(4)+x)+(sinx-cosx)^(2), AA x in R then max(f(x))...

    Text Solution

    |