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 passing through the point (?2, 4) and through the points of intersection of the circle \[{{x}^{2}}+{{y}^{2}}-2x-6y+6=0\] and the line \[3x+2y-5=0\], is [RPET 1996]

    A)            \[{{x}^{2}}+{{y}^{2}}+2x-4y-4=0\]                              

    B)            \[{{x}^{2}}+{{y}^{2}}+4x-2y-4=0\]

    C)            \[{{x}^{2}}+{{y}^{2}}-3x-4y=0\]                                    

    D)            \[{{x}^{2}}+{{y}^{2}}-4x-2y=0\]

    Correct Answer: B

    Solution :

               Required equation of the circle,                    \[({{x}^{2}}+{{y}^{2}}-2x-6y+6)+\lambda (3x+2y-5)=0\]                    This circle passing through points\[(-2,\ 4)\], therefore                    \[(4+16+4-24+6)+\lambda (-6+8-5)=0\], \[\therefore \ \lambda =2\]                    \[\therefore \ ({{x}^{2}}+{{y}^{2}}-2x-6y+6)+2(3x+2y-5)=0\]                        \[\Rightarrow {{x}^{2}}+{{y}^{2}}+4x-2y-4=0\].


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