CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    The distance between the vertex of the parabola\[y={{x}^{2}}-4x+3\]and the centre of the circle\[{{x}^{2}}=9-{{(y-3)}^{2}}\]is

    A)  \[2\sqrt{3}\]                                     

    B)  \[3\sqrt{2}\]

    C)  \[2\sqrt{2}\]                     

    D)         \[\sqrt{2}\]

    E)  \[2\sqrt{5}\]

    Correct Answer: E

    Solution :

    Given equation of parabola, \[y={{x}^{2}}-4x+3\] \[\Rightarrow \]               \[(y+1)={{x}^{2}}-4x+4\] \[\Rightarrow \]               \[{{(x-2)}^{2}}=(y+1)\] Comparing with, \[{{X}^{2}}=4aY\]here\[X=x-2\]and \[y=y+1,a=\frac{1}{4}\] Vertex is\[(2,-1)=V\](say) equation of circle, \[{{x}^{2}}=9-{{(y-3)}^{2}}\] or   \[{{(x-0)}^{2}}+{{(y-3)}^{2}}=9\] Centre \[C=(0,\text{ }3)\] Now, \[VC=\sqrt{{{(2-0)}^{2}}+{{(-1-3)}^{2}}}\]                 \[=\sqrt{4+16}=\sqrt{20}\]                 \[=2\sqrt{5}\]


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