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 origin and cuts off intercepts of 2 units length from negative coordinate axes, is

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

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

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

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

    Correct Answer: C

    Solution :

               Since the circle passes through (0, 0), hence\[c=0\].  Also \[2\sqrt{{{g}^{2}}-c}=2\Rightarrow g=1\]                    and \[2\sqrt{{{f}^{2}}-c}=2\Rightarrow f=1\].                    Hence radius is \[\sqrt{2}\] and centre is\[(-1,\ -1)\]. Therefore, the required equation is\[{{x}^{2}}+{{y}^{2}}+2x+2y=0\]. Trick: Obviously the centre of circle lies in III quadrant, which is given by (c).


You need to login to perform this action.
You will be redirected in 3 sec spinner