Home
Class 11
MATHS
If cos alpha+cos beta=0=sin alpha+sin be...

If `cos alpha+cos beta=0=sin alpha+sin beta`, then `cos 2 alpha+cos 2beta` is equal to

A

`-2sin(alpha+beta)`

B

`-2cos(alpha+beta)`

C

`2sin(alpha+beta)`

D

`2cos(alpha+beta)`

Text Solution

Verified by Experts

The correct Answer is:
B
Promotional Banner

Topper's Solved these Questions

  • COMPOUND ANGLES

    AAKASH SERIES|Exercise PRACTICE SHEET (EXERCISE - I) LEVEL - II|4 Videos

  • COMPOUND ANGLES

    AAKASH SERIES|Exercise ADDITIONAL PRACTICE EXERCISE (LEVEL - I (MAIN))|14 Videos

  • COMPOUND ANGLES

    AAKASH SERIES|Exercise LECTURE SHEET (EXERCISE - I)|43 Videos

  • CHANGE OF AXES

    AAKASH SERIES|Exercise Practice Exercise|29 Videos

  • CONTINUITY

    AAKASH SERIES|Exercise ADVANCED SUBJECTIVE TYPE QUESTIONS|34 Videos

Similar Questions

Explore conceptually related problems

If cos alpha + cos beta =0 = sin alpha + sin beta " then " cos (alpha - beta )=

If sin alpha = sin beta and cos alpha = cos beta then

If alpha, beta are solutions of a cos theta + b sin theta = c where a, b, c in R and a^(2) + b^(2) gt 0, cos alpha ne cos beta, sin alpha ne sin beta then prove that cos alpha cos beta = (c^(2) - b^(2))/(a^(2) + b^(2))

If alpha, beta are solutions of a cos theta + b sin theta = c where a, b, c in R and a^(2) + b^(2) gt 0, cos alpha ne cos beta, sin alpha ne sin beta then prove that cos alpha + cos beta = (2ac)/(a^(2) + b^(2))

sin alpha=sinbeta, cos alpha=cos beta then

If cos alpha+ cos beta= a, sin alpha+ sin beta= b and alpha- beta= 2 theta . Then (cos 3 theta)/(cos theta)=

If alpha, beta are solutions of a cos theta + b sin theta = c where a, b, c in R and a^(2) + b^(2) gt 0, cos alpha ne cos beta, sin alpha ne sin beta then prove that sin alpha sin beta = (c^(2)-a^(2))/(a^(2) + b^(2))

If alpha, beta are solutions of a cos theta + b sin theta = c where a, b, c in R and a^(2) + b^(2) gt 0, cos alpha ne cos beta, sin alpha ne sin beta then prove that sin alpha + sin beta = (2bc)/(a^(2) + b^(2))

AAKASH SERIES-COMPOUND ANGLES-PRACTICE SHEET (EXERCISE - I) LEVEL - I
  1. If cos 28^(@)+sin 28^(@)=k^(3), then cos17^(@) equal to

    Text Solution

    |

  2. If (x)/( cos theta ) = (y) /( cos (theta - 2pi//3))=(z)/( cos ( theta ...

    Text Solution

    |

  3. If cos alpha+cos beta=0=sin alpha+sin beta, then cos 2 alpha+cos 2beta...

    Text Solution

    |

  4. Let f(n)=2 cos nx AA n in N, then f(1)f(n+1)-f(n) is equal to

    Text Solution

    |

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

    Text Solution

    |

  6. If (cosx)/(cosy)=2 and cos (x-y)=(sqrt(3))/(2) then tan y=

    Text Solution

    |

  7. If tan beta = 2 sin alpha sin gamma " cosec "(alpha + gamma) , then ...

    Text Solution

    |

  8. Assertion (A): tan40^(@) + tan 80^(@) - sqrt(3)tan 40^(@) tan80^(@)=-s...

    Text Solution

    |

  9. Statement-I : If 0 lt alpha, beta lt pi/4, sin alpha =a/sqrt(1+a^(2)),...

    Text Solution

    |

  10. I : If x cos theta = y cos (120^@ + theta ) = z cos ( theta + 240^(@)...

    Text Solution

    |

  11. Statement I: If sin alpha = 12/13, (0 lt alpha lt pi/2) and cos beta =...

    Text Solution

    |

  12. If A=35^(@) , B= 15^(@) and C=40^(@) , then tan A* tan B+ tan B* tan...

    Text Solution

    |

  13. In an acute angled triangle, cot B cot C + cot A cot C + cot A cot B

    Text Solution

    |

  14. Arrange the following values in the ascending order of P,Q,R. If A+B+C...

    Text Solution

    |

  15. In triangle ABC, tan A + tan B + tan C = 6 and tanA tanB = 2, then the...

    Text Solution

    |

  16. Statement I : If m cos(theta+alpha)=n cos (theta-alpha) then tan theta...

    Text Solution

    |

  17. Let A=pi/7, B =(2pi)/7, C=(4pi)/7 and cosA cos B cosC=-1//8, then 2sum...

    Text Solution

    |

  18. If cos 2B=(cos (A+C))/(cos(A-C)) , then tan A , tan B , tan C are in

    Text Solution

    |

  19. If 2sec2theta = tan phi + cot phi, then one of the values of theta + p...

    Text Solution

    |

  20. If cos25^(@)+sin25^(@)=p, then cos 50^(@) is

    Text Solution

    |