Home
Class 12
MATHS
If 1+cos alpha+cos ^(2) alpha+….=2-sqrt(...

If `1+cos alpha+cos ^(2) alpha+….=2-sqrt(2)`, then`alpha(0 lt alpha lt pi)` is

A

`(pi)/(4)`

B

`(pi)/(8)`

C

`(3 pi)/(4)`

D

`(pi)/(6)`

Text Solution

Verified by Experts

Promotional Banner

Topper's Solved these Questions

  • MAXIMA AND MINIMA

    HIMALAYA PUBLICATION|Exercise QUESTION BANK|167 Videos

  • Pair Of Lines

    HIMALAYA PUBLICATION|Exercise QUESTION BANK|129 Videos

Similar Questions

Explore conceptually related problems

If sin alpha, sin^(2) alpha, 1,sin^(4) alpha, sin^(5) alpha, ( - pi lt alpha lt pi ) are in A.P. , then alpha lies in the interval :

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

The sides of a triangle are sinalpha,cosalpha and sqrt(1+sinalphacosalpha) for some 0 lt alpha lt (pi)/(2) . The the greatest angle of the triangle is

If a variable takes the discrete values : alpha + 4, alpha - (7)/(2), alpha - (5)/(2), alpha - 3, alpha - 2, alpha + (1)/(2), alpha - (1)/(2), alpha + 5, (alpha gt 0) , then the median is :

Show that sqrt((1+cos alpha)/(1-cos alpha))=cosec alpha + cot alpha

If A=[[cos alpha, -sin alpha] , [sin alpha, cos alpha]], B=[[cos2beta, sin 2beta] , [sin 2 beta, -cos2beta]] where 0 lt beta lt pi/2 then prove that BAB=A^(-1) Also find the least positive value of alpha for which BA^4B= A^(-1)

"Evaluate "Delta ={:|( 0 , sin alpha ,-cos alpha ) ,( -sin alpha , 0 , sin beta ),( cos alpha , -sin beta , 0)|:}

If cos (alpha+beta)=(4)/(5), sin (alpha-beta)=(5)/(13) and 0 lt alpha, beta lt (pi)/(2) then cos 2 alpha=

HIMALAYA PUBLICATION-MEASUREMENT OF ANGLES, TRIGONOMETRIC RATIOS AND RELATION BETWEEN SIDES AND ANGLES OF A TRIANGLE-QUESTION BANK
  1. If tan 25^(circ)=x, then (tan 155^(circ)-tan 115^(circ))/(1+tan 155^(c...

    Text Solution

    |

  2. If x + y + z = pi,tanx tany = 2tanx + tany + tanz = 6, thenz equals :

    Text Solution

    |

  3. If 1+cos alpha+cos ^(2) alpha+….=2-sqrt(2), thenalpha(0 lt alpha lt pi...

    Text Solution

    |

  4. The value of the determinant : |(sin^(2)13^(@)""sin^(2)77^(@)""tan135^...

    Text Solution

    |

  5. If tan A+tan B+tan C=tan A . tan B . tan C then

    Text Solution

    |

  6. In a right angled triangle, the hypotenuse four times as long as the p...

    Text Solution

    |

  7. If sin theta+cos theta=a then sin ^(4) theta+cos ^(4) theta=

    Text Solution

    |

  8. If sin x+sin ^(2) x=1 then the value of cos ^(2) x+cos ^(4) x is

    Text Solution

    |

  9. In a Delta ABC angle A is greater than B. If the measures of angles A ...

    Text Solution

    |

  10. cos ^(2) (3 pi)/(5)+cos ^(2) (4 pi)/(5)=

    Text Solution

    |

  11. cot theta=sin 2 theta,(theta ne n pi), if theta

    Text Solution

    |

  12. If (pi)/(2) lt theta lt (3 pi)/(2) then sqrt((1-sin theta)/(1+sin thet...

    Text Solution

    |

  13. If alpha in[-pi, pi] such that sqrt((1-sin alpha)/(1+sin alpha))=sec a...

    Text Solution

    |

  14. If -(pi)/(4)lt A lt (pi)/(4), then (sqrt(1+sin 2 A)+sqrt(1-sin 2 A))/(...

    Text Solution

    |

  15. If tan theta = -4/3, then sin theta is :

    Text Solution

    |

  16. The greatest value of sin x cos x is

    Text Solution

    |

  17. The value of sin 20^(circ) sin 40^(circ) sin 60^(circ) sin 80^(circ) i...

    Text Solution

    |

  18. The value of cos (pi)/(5) . cos (2 pi)/(5). cos (4 pi)/(5) . cos (8 pi...

    Text Solution

    |

  19. If sin theta+cosec theta=2, then sin ^(2) theta+cosec^(2) theta=

    Text Solution

    |

  20. If f(x)=cos ^(2) x+sec ^(2) x, then

    Text Solution

    |