JEE Main & Advanced Mathematics Conic Sections Question Bank Ellipse

  • question_answer
    The eccentricity of an ellipse is 2/3, latus rectum is 5 and centre is (0, 0). The equation of the ellipse is

    A)            \[\frac{{{x}^{2}}}{81}+\frac{{{y}^{2}}}{45}=1\]                            

    B)            \[\frac{4{{x}^{2}}}{81}+\frac{4{{y}^{2}}}{45}=1\]

    C)            \[\frac{{{x}^{2}}}{9}+\frac{{{y}^{2}}}{5}=1\]                                

    D)            \[\frac{{{x}^{2}}}{{{a}^{2}}}+\frac{{{y}^{2}}}{{{b}^{2}}}=1\]

    Correct Answer: B

    Solution :

               \[{{\left( \frac{2}{3} \right)}^{2}}=1-\frac{{{b}^{2}}}{{{a}^{2}}}\] and \[\frac{2{{b}^{2}}}{a}=5\] Þ \[a=\frac{81}{4}\], \[b=\frac{45}{4}\] Hence the equation is\[\frac{4{{x}^{2}}}{81}+\frac{4{{y}^{2}}}{45}=1\].


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