Home
Class 11
MATHS
cos theta + cos 2 theta + cos 3 theta + ...

`cos theta + cos 2 theta + cos 3 theta + …. + cos { (n-1) theta}+ cos n theta=`

A

`(cos { (1)/(2) (n+1) theta} . Sin((ntheta)/( 2) ))/( sin((theta)/(2)) )`

B

`(cos (n+1) theta)/( sin ((theta)/( 2)) )`

C

`( cos ( ((n-1) theta)/(2) ) sin ( ( n theta)/( 2) ) )/( sin"" ( theta)/( 2) )`

D

`(sin ( (n theta)/( 2) ).cos{ (n+1) theta})/( sin ((theta)/( 2) ) )`

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Topper's Solved these Questions

  • MATHEMATICAL INDUCTION

    AAKASH SERIES|Exercise PRACTICE SHEET (EXERCISE-I) LEVEL-I (Principle of Mathematical Induction) (Straight Objective Type Questions)|55 Videos

  • LOCUS

    AAKASH SERIES|Exercise PRACTICE EXERCISE|37 Videos

  • MATRICES

    AAKASH SERIES|Exercise LINEAR EQUATIONS - PRACTICE EXERCISE|15 Videos

Similar Questions

Explore conceptually related problems

( cos 6 theta +6 cos 4 theta + 15 cos 2 theta + 10)/( cos 5 theta + 5 cos 3 theta + 10 cos theta)=

2 cos theta - cos 3 theta - cos 5 theta - 16 cos^(3) theta sin^(2) theta =

If cos theta + cos 7 theta + cos 3 theta + cos 5 theta = 0 " then " theta =

If cos theta cos 2 theta cos 3theta = 1//4 for 0 lt theta lt pi then theta =

( sin 3 theta + sin 5 theta + sin 7 theta + sin 9 theta)/( cos 3 theta + cos 5 theta + cos 7 theta + cos 9 theta) is equal to

If 0 lt theta lt pi/2 , the solution of the equation sin theta - 3 sin 2 theta + sin 3 theta = cos theta - 3 cos 2 theta + cos 3 theta is

1+ cos 2 theta + cos 4 theta + cos 6 theta =

If cos theta + cos 2theta + cos 3theta = 0 then theta =

AAKASH SERIES-MATHEMATICAL INDUCTION-PRACTICE SHEET (EXERCISE-I) LEVEL-I (Principle of Mathematical Induction) (Straight Objective Type Questions)
  1. sum(n=0)^( oo) (-1)^(n) x^( n+1)=

    Text Solution

    |

  2. sum(k=1)^(2n+1) (-1)^(k-1) k^2 =

    Text Solution

    |

  3. cos theta + cos 2 theta + cos 3 theta + …. + cos { (n-1) theta}+ cos n...

    Text Solution

    |

  4. If P (n) = 1+2+3+ …. + n is a perfect square N^(2) and N is less than...

    Text Solution

    |

  5. 1 + (x)/( a1) + ( x( x+a1) )/( a1 a2 ) + .... + ( x ( x+a1) (x+ a2)......

    Text Solution

    |

  6. (1)/(2) tan"" ((x)/(2) ) + (1)/( 4) (tan"" (x)/(4) ) + ...... + (1)/(2...

    Text Solution

    |

  7. For any integer n ge 1, then sum(k=1)^(n) k ( k+2) is equal to

    Text Solution

    |

  8. S(n) = 1^(3) + 2^(3) + 3^(3) + …... + n^(3) and T(n) = 1+ 2 + 3+ 4….....

    Text Solution

    |

  9. A = sum of first 10 natural numbers, B = sum of squares of first 10 ...

    Text Solution

    |

  10. If sum (r=1)^(n) t(r) = (1)/( 12) n (n+1) (n+2) then sum(r=1)^(n) (1)...

    Text Solution

    |

  11. 1+ (1+3) + (1+3+ 5) + ….n brackets =

    Text Solution

    |

  12. 1+ ((1)/(3) + (1)/(3^2) ) + (( 1)/( 3^3) + (1)/( 3^4) + (1)/( 3^5) ) ...

    Text Solution

    |

  13. Sum of n^( th) bracket of (1) + (2+ 3+4) + ( 5+ 6+ 7+ 8+9) + ….. is

    Text Solution

    |

  14. { n (n+1) (2n+1) : n in Z} sub

    Text Solution

    |

  15. If a,b and n are natural numbers then a^(2n-1) + b^(2n-1) is divisible...

    Text Solution

    |

  16. If 'a' and 'b'are natural numbers such that a^(2) - b^(2) is prime num...

    Text Solution

    |

  17. AA n in N, 49^(n) + 16n -1 is divisible by

    Text Solution

    |

  18. AA n in , 7^(2n) + 3^(n-1) . 2^(3n-3) is divisible by

    Text Solution

    |

  19. Sum of the cubes of three successive natural number is divisible by

    Text Solution

    |

  20. For every natural number n, 3^(2n+2) - 8n -9 is divisible by

    Text Solution

    |