CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2002

  • question_answer
    The centre of a circle is\[(2,-3)\]and the circumference is\[10\pi \]Then the equation of the circle is:

    A)  \[{{x}^{2}}+{{y}^{2}}+4x+6y+12=0.\]

    B)         \[{{x}^{2}}+{{y}^{2}}-4x+6y+12=0\]

    C)         \[{{x}^{2}}+{{y}^{2}}-4x+6y-12=0\]

    D)         \[{{x}^{2}}+{{y}^{2}}-4x-6y-12=0\]

    E)         \[{{x}^{2}}+{{y}^{2}}-4x-6y+12=0\]

    Correct Answer: C

    Solution :

    \[\because \]Circumference of circle \[=10\pi \] \[\Rightarrow \] \[2\pi r=10\pi \]              \[\Rightarrow \] \[r=5\] \[\therefore \]Equation of circle whose centre is\[(2,-3)\]and radius 5, is \[{{(x-2)}^{2}}+{{(y+3)}^{2}}={{5}^{2}}\] \[\Rightarrow \]               \[{{x}^{2}}+{{y}^{2}}-4x+6y+13=25\] \[\Rightarrow \]               \[{{x}^{2}}+{{y}^{2}}-4x+6y-12=0\]


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