CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2003

  • question_answer
    The distance between the directories of the hyperbola \[x=8\sec \theta ,\,y=8\,\tan \theta \] is :

    A)  \[8\sqrt{2}\]

    B)  \[16\sqrt{2}\]

    C)  \[4\sqrt{2}\]                                     

    D)  \[6\sqrt{2}\]

    Correct Answer: A

    Solution :

    Here we have \[x=8\,\sec \theta ,\,y=8\,\tan \theta \] \[{{x}^{2}}=64{{\sec }^{2}}\theta ,\,{{y}^{2}}=64\,{{\tan }^{2}}\theta \] \[\therefore \]  \[{{x}^{2}}-{{y}^{2}}=64\,({{\sec }^{2}}\theta -{{\tan }^{2}}\theta )\]                 \[{{x}^{2}}-{{y}^{2}}=64\] \[\therefore \] It is a rectangular parabola whose eccentricity is \[\sqrt{2}\]. \[\therefore \] We have distance between directories                 \[=\frac{2a}{e}\]                 \[=\frac{2\times 8}{\sqrt{2}}\]                 \[=8\sqrt{2}\]                                


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