JEE Main & Advanced Mathematics Circle and System of Circles Question Bank Equations of circle, Geometrical problems regarding circle

  • question_answer
    The equation of the circle which passes through the points \[(3,\ -2)\] and \[(-2,\ 0)\] and centre lies on the line \[2x-y=3\], is [Roorkee 1971]

    A)            \[{{x}^{2}}+{{y}^{2}}-3x-12y+2=0\]

    B)            \[{{x}^{2}}+{{y}^{2}}-3x+12y+2=0\]

    C)            \[{{x}^{2}}+{{y}^{2}}+3x+12y+2=0\]

    D)            None of these

    Correct Answer: C

    Solution :

               Let centre be (h, k), then                    \[{{(h-3)}^{2}}+{{(k+2)}^{2}}={{(h+2)}^{2}}+{{k}^{2}}\]                    \[\Rightarrow 10h-4k-9=0\]                    Also the centre lies on the given line, so \[2h-k=3\].                    On solving \[k=-6,\ h=-\frac{3}{2}\]                    Radius is\[{{(h-3)}^{2}}+{{(k+2)}^{2}}=\frac{145}{4}\], which is true for option (c) only.


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