JEE Main & Advanced Mathematics Conic Sections Question Bank Self Evaluation Test - Conic Sections

  • question_answer
    Let \[{{S}_{1}},{{S}_{2}}\] be the foci of the ellipse, \[\frac{{{x}^{2}}}{16}+\frac{{{y}^{2}}}{8}=1\]. If \[A(x+y)\] is any point on the ellipse, then the maximum area of the triangle \[A{{S}_{1}}{{S}_{2}}\] (in square units) is

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

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

    C) 8

    D) 4

    Correct Answer: C

    Solution :

    [c] Equation of ellipse is \[\frac{{{x}^{2}}}{16}+\frac{{{y}^{2}}}{8}=1\] where, \[a=4,b=2\sqrt{2}\] Eccentricity, \[e=\sqrt{1-\frac{{{b}^{2}}}{{{a}^{2}}}}=\sqrt{1-\frac{8}{16}}=\frac{1}{\sqrt{2}}\] Area is maximum when vertex is (0, b) \[\therefore \] Maximum area \[=\frac{1}{2}\times 2ae\times b\] \[=\frac{1}{2}\times 2\times 4\times 2\sqrt{2}\times \frac{1}{\sqrt{2}}=8\] sq. units


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