Home
Class 11
MATHS
If in A B C ,A=pi/7,B=(2pi)/7,C=(4pi)/7...

If in ` A B C ,A=pi/7,B=(2pi)/7,C=(4pi)/7` then `a^2+b^2+c^2` must be (a)`R^2` (b) `3R^2` (c) `4R^2` (d) `7R^2`

Promotional Banner

Topper's Solved these Questions

  • STRAIGHT LINES

    CENGAGE PUBLICATION|Exercise All Questions|486 Videos

Similar Questions

Explore conceptually related problems

If (3-tan^2(pi/7))/(1-tan^2(pi/7))=kcos(pi/7) then the value of k is (a)1 (b) 2 (c) 3 (d) 4

If the equation x^3+b x^2+c x+1=0,(b (a) -pi (b) -pi/2 (c) pi/2 (d) pi

If (sinx)(cosy)=1/2, then (d^2y)/(dx^2) at (pi/4,pi/4) is (a) -4 (b) -2 (c) -6 (d) 0

If A+B+C=(3pi)/2 , then cos2A +cos2B+cos2C is

cos((2pi)/7)+cos((4pi)/7)+cos((6pi)/7)

In an acute angled triangle A B C ,r+r_1=r_2+r_3a n d/_B >pi/3, then (a) b+2c<2a<2b+2c (b) b+4c<4a<2b+4c (c) b+4c<4a<4b+4c (d) b+3c<3a<3b+3c

With usual notations, in triangle A B C ,acos(B-C)+bcos(C-A)+c"cos"(A-B) is equal to(a) (a b c)/R^2 (b) (a b c)/(4R^2) (c) (4a b c)/(R^2) (d) (a b c)/(2R^2)

If [(cos(2pi)/7,-sin(2pi)/7),(sin(2pi)/7, cos(2pi)/7)]^k=[(1,0 ),(0 ,1)] , then the least positive integral value of k is (a) 3 (b) 4 (c) 6 (d) 7

In triangle A B C , if r_1=2r_2=3r_3, then a : b is equal to 5/4 (b) 4/5 (c) 7/4 (d) 4/7

In A B C ,cotA/2+cotB/2+cotC/2 is equal to Delta/(r^2) (b) ((a+b+c)^2)/(a b c)2R (c) Delta/r (d) Delta/(R r)

CENGAGE PUBLICATION-TRIGONOMETRIC FUNCTIONS-All Questions
  1. In a triangle ABC, (a+b+c)(b+c-a)=kbc if

    Text Solution

    |

  2. The equation e^(sin x) -e^(-sin x)-4=0 has

    Text Solution

    |

  3. If in A B C ,A=pi/7,B=(2pi)/7,C=(4pi)/7 then a^2+b^2+c^2 must be (a)R...

    Text Solution

    |

  4. If x in (0,2pi)a n dy in (0,2pi) , then find the number of distinct or...

    Text Solution

    |

  5. In a triangle A B CifB C=1 and AC=2, then what is the maximum possible...

    Text Solution

    |

  6. Find the number of roots of the equation 16sec^3theta-12tan^2theta-4se...

    Text Solution

    |

  7. If a^2, b^2,c^2 are in A.P., then prove that tanA ,tanB ,tanC are in H...

    Text Solution

    |

  8. If 2tan^2x-5secx=1 for exactly seven distinct value of x in [0,(npi)/2...

    Text Solution

    |

  9. If an a triangle A B C , b=3 c, a n d C-B=90^0, then find the value o...

    Text Solution

    |

  10. The real roots of the equation cos^7x+sin^4x=1 in the interval (-pi,pi...

    Text Solution

    |

  11. If the base angles of triangle are ((22)/(12))^@ and (112 1/2)^@ , th...

    Text Solution

    |

  12. The general solution of the trigonometric equation sinx+cosx=1 is give...

    Text Solution

    |

  13. Prove that: (sin(B-C))/(cosBcosC)+(sin(C-A))/(cosCcosA)+(sin(A-B))/(co...

    Text Solution

    |

  14. The equation 2cos^2 (x/2)sin^2x=x^2+x^(-2);0

    Text Solution

    |

  15. The perimeter of a triangle ABC is saix times the arithmetic mean of ...

    Text Solution

    |

  16. One of the general solutions of 4sinthetasin2thetasin4theta=sin3theta ...

    Text Solution

    |

  17. If A=75^@,B=45^@, then prove that b+csqrt(2)=2a

    Text Solution

    |

  18. The general solution of the equation 8cosxcos2xcos4x=(sin6x)/(sin x) ...

    Text Solution

    |

  19. in triangleABC if (a^2+b^2)/(a^2-b^2)=sin(A+B)/sin(A-B) then prove th...

    Text Solution

    |

  20. (sin^3theta-cos^3theta)/(sintheta-costheta)-(costheta)/(sqrt(1+cot^2th...

    Text Solution

    |