BCECE Engineering BCECE Engineering Solved Paper-2001

  • question_answer
    The equation of the diameter of the circle \[{{x}^{2}}+{{y}^{2}}+2x-4y-11=0\] which bisects the chords intercepted on the line \[2x-y+3=0\]  is:

    A) \[x+y-7=0\]       

    B) \[2x-y-5=0\]

    C)                        \[~x+2y-3=0\]  

    D)         none of these

    Correct Answer: C

    Solution :

    Key Idea: The perpendicular distance from centre to the chord its bisects the chord. Given equation of circle is \[{{x}^{2}}+{{y}^{2}}+2x-4y-11=0\] \[\therefore \] Centre is, \[(-1,2).\] Since, the diameter of the circle is perpendicular to the chord of the circle.  Hence, the equation of diameter is \[x+2y+\lambda =0\]                                     ...(i) Its passes through the centre \[(-1,2)\] of the circle                 \[\Rightarrow \]               \[-1+4+\lambda =0\]\[\Rightarrow \]\[\lambda =-3\] Putting the value of \[\lambda \] in Eq. (i), we get \[x+2y-3=0\]


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