JEE Main & Advanced Mathematics Conic Sections Question Bank Hyperbola

  • question_answer
    The equation of the hyperbola whose foci are the foci of the ellipse \[\frac{{{x}^{2}}}{25}+\frac{{{y}^{2}}}{9}=1\] and the eccentricity is 2, is

    A)            \[\frac{{{x}^{2}}}{4}+\frac{{{y}^{2}}}{12}=1\]                              

    B)            \[\frac{{{x}^{2}}}{4}-\frac{{{y}^{2}}}{12}=1\]

    C)                                 \[\frac{{{x}^{2}}}{12}+\frac{{{y}^{2}}}{4}=1\]                              

    D)            \[\frac{{{x}^{2}}}{12}-\frac{{{y}^{2}}}{4}=1\]

    Correct Answer: B

    Solution :

                      Here for given ellipse \[a=5,\ b=3,\ {{b}^{2}}={{a}^{2}}(1-{{e}^{2}})\]Þ \[e=\frac{4}{5}\]                   Therefore, focus is (? 4, 0), (4, 0).                   Given eccentricity of hyperbola = 2                   \[a=\frac{ae}{e}=\frac{4}{2}=2\] and \[b=2\sqrt{(4-1)}=2\sqrt{3}\]                    Hence hyperbola is \[\frac{{{x}^{2}}}{4}-\frac{{{y}^{2}}}{12}=1\].


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