Manipal Engineering Manipal Engineering Solved Paper-2011

  • question_answer
    The diameter of\[16{{x}^{2}}-9{{y}^{2}}=144\]which is conjugate to\[x=2y\]is

    A) \[y=\frac{32x}{9}\]                         

    B) \[x=\frac{16}{9}y\]

    C) \[y=\frac{16}{9}x\]         

    D)         None of these

    Correct Answer: A

    Solution :

    The diameters\[y={{m}_{1}}x\]and\[y={{m}_{2}}x\]are conjugate diameters of the hyperbola                 \[\frac{{{x}^{2}}}{{{a}^{2}}}-\frac{{{y}^{2}}}{{{b}^{2}}}=1\], if\[{{m}_{1}}{{m}_{2}}=\frac{{{b}^{2}}}{{{a}^{2}}}\] Given equation is                 \[\frac{{{x}^{2}}}{9}\cdot \frac{{{y}^{2}}}{16}=1\] Here,     \[{{a}^{2}}=9,\,\,{{b}^{2}}=16\] Also given,\[x=2y\] Then,    \[{{m}_{1}}=\frac{1}{2}\] \[\because \]     \[\frac{1}{2}\times {{m}_{2}}=\frac{16}{9}\] \[\Rightarrow \]               \[{{m}_{2}}=\frac{32}{9}\] Hence, the required equation of diameter is                 \[y=\frac{32x}{9}\]


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