JEE Main & Advanced AIEEE Solved Paper-2002

  • question_answer
    The equation of the ellipse whose foci are \[(\pm \,2,0)\] and eccentricity is \[1/2\], is AIEEE  Solved  Paper-2002

    A) \[\frac{{{x}^{2}}}{12}+\frac{{{y}^{2}}}{16}=1\]                       

    B) \[\frac{{{x}^{2}}}{16}+\frac{{{y}^{2}}}{12}=1\]       

    C)           \[\frac{{{x}^{2}}}{16}+\frac{{{y}^{2}}}{8}=1\]      

    D)           None of these

    Correct Answer: B

    Solution :

    The foci of an ellipse \[\frac{{{x}^{2}}}{{{\alpha }^{2}}}+\frac{{{y}^{2}}}{{{b}^{2}}}=1\] is given by\[(\pm \,ae,\,\,0)\]. Since, \[e=\frac{1}{2},\,\,ae=2\]              \[\Rightarrow \]   \[a=4\]              \[\therefore \]     \[{{b}^{2}}={{a}^{2}}(1-{{e}^{2}})-16\left( 1-\frac{1}{4} \right)=12\]              Hence, the equation of an ellipse is \[\frac{{{x}^{2}}}{16}+\frac{{{y}^{2}}}{12}=1\]


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