JEE Main & Advanced Mathematics Conic Sections Question Bank Hyperbola

  • question_answer
    The value of m for which \[y=mx+6\] is a tangent to the hyperbola \[\frac{{{x}^{2}}}{100}-\frac{{{y}^{2}}}{49}=1\], is   [Karnataka CET 1993]

    A)            \[\sqrt{\frac{17}{20}}\]            

    B)            \[\sqrt{\frac{20}{17}}\]

    C)            \[\sqrt{\frac{3}{20}}\]              

    D)            \[\sqrt{\frac{20}{3}}\]

    Correct Answer: A

    Solution :

               If \[y=mx+c\] touches \[\frac{{{x}^{2}}}{{{a}^{2}}}-\frac{{{y}^{2}}}{{{b}^{2}}}=1,\]                    then \[{{c}^{2}}={{a}^{2}}{{m}^{2}}-{{b}^{2}}\]. Here \[c=6,\,\,{{a}^{2}}=100,\,\,{{b}^{2}}=49\]                    \[\therefore 36=100{{m}^{2}}-49\Rightarrow 100{{m}^{2}}=85\Rightarrow m=\sqrt{\frac{17}{20}}\].


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