CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2008

  • question_answer
    The circles\[{{x}^{2}}+{{y}^{2}}-4x-6y-12=0\]and \[{{x}^{2}}+{{y}^{2}}+4x+6y+4=0\]

    A)  touch externally

    B)  do not intersect

    C)  touch internally

    D)  intersect at two points

    E)  are concentric

    Correct Answer: D

    Solution :

    The centres and radii of given circles \[{{x}^{2}}+{{y}^{2}}-4x-6y-12=0\]and \[{{x}^{2}}+{{y}^{2}}+4x+6y+4=0\]are \[{{C}_{2}}(2,3),{{C}_{2}}(-2,-3)\]and                 \[{{r}_{1}}=\sqrt{4+9+12}=5,\]                 \[{{r}_{2}}=\sqrt{4+9-4}=3\] Now, \[{{C}_{1}}{{C}_{2}}=\sqrt{{{(2+2)}^{2}}+{{(3+3)}^{2}}}=\sqrt{52}\] Here, \[{{C}_{1}}{{C}_{2}}<{{r}_{1}}+{{r}_{2}}\] Hence, given circles intersect at two points.


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