CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
    Two diameters of the circle\[3{{x}^{2}}+3{{y}^{2}}-6x\]\[-18y-7=0\]are along the lines\[3x+y=q\] and\[x-3y={{c}_{2}}\].Then the value of\[{{c}_{1}}{{c}_{2}}\]is

    A)  \[-\,48\]

    B)                                         80

    C)  \[-\,72\]             

    D)         54

    E)  24

    Correct Answer: A

    Solution :

    The equation of circle is \[3{{x}^{2}}+3{{y}^{2}}-6x-18y-7=0\] \[\Rightarrow \]               \[{{x}^{2}}+{{y}^{2}}-2x-6y-\frac{7}{3}=0\] The centre of this circle is (1, 3). Also, two diameters of this circle are along the lines\[3x+y=q\]and\[x-3y={{c}_{2}}\] These two diameters should be passed from (1, 3). \[\therefore \] \[{{c}_{1}}=6\]and\[{{c}_{2}}=-8\] Hence, \[{{c}_{1}}{{c}_{2}}=6\times (-8)=-48\]


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