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 whose diameter lies on \[2x+3y=3\]and \[16x-y=4\] which passes through (4,6)  is [Kurukshetra CEE 1998]

    A)            \[5\text{ }({{x}^{2}}+{{y}^{2}})-3x-8y=200\]

    B)            \[{{x}^{2}}+{{y}^{2}}-4x-8y=200\]

    C)            \[5\text{ }({{x}^{2}}+{{y}^{2}})-4x=200\]                    

    D)            \[{{x}^{2}}+{{y}^{2}}=40\]

    Correct Answer: A

    Solution :

               Let point \[({{x}_{1}},\ {{y}_{1}})\] on the diameter.                    \[\Rightarrow 2{{x}_{1}}+3{{y}_{1}}=3\]                                                             ?.(i)                    \[16{{x}_{1}}-{{y}_{1}}=4\]                                                        ?.(ii)                    On solving (i) and (ii), we get centre,                    \[\Rightarrow {{x}_{1}}=\frac{3}{10},\ {{y}_{1}}=\frac{4}{5}\]                    \[\therefore \] Equation of circle,     \[{{(x-{{x}_{1}})}^{2}}+{{(y-{{y}_{1}})}^{2}}={{r}^{2}}\Rightarrow {{\left( x-\frac{3}{10} \right)}^{2}}+{{\left( y-\frac{4}{5} \right)}^{2}}={{r}^{2}}\]                    \[\because \] Circle passes through (4, 6).                    So, \[{{r}^{2}}={{\left( \frac{37}{10} \right)}^{2}}+{{\left( \frac{26}{5} \right)}^{2}}\Rightarrow {{r}^{2}}=\frac{4073}{100}\]                    \[\therefore \] Required equation of circle is                    \[{{\left( x-\frac{3}{10} \right)}^{2}}+{{\left( y-\frac{4}{5} \right)}^{2}}=\frac{4073}{100}\]                    \[\Rightarrow 5({{x}^{2}}+{{y}^{2}})-3x-8y=200\].


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