JEE Main & Advanced Mathematics Conic Sections Question Bank Hyperbola

  • question_answer
    The latus rectum of the hyperbola \[9{{x}^{2}}-16{{y}^{2}}+72x-32y-16=0\] is   [Pb. CET 2004]

    A)            \[\frac{9}{2}\]                           

    B)            \[-\frac{9}{2}\]

    C)            \[\frac{32}{3}\]                         

    D)            \[-\frac{32}{3}\]

    Correct Answer: A

    Solution :

               Given equation of hyperbola is, \[9{{x}^{2}}-16{{y}^{2}}+72x-32y-16=0\] Þ \[9\,({{x}^{2}}+8x)-16\,({{y}^{2}}+2y)-16=0\] Þ \[9\,{{(x+4)}^{2}}-16{{(y+1)}^{2}}=144\] Þ \[\frac{{{(x+4)}^{2}}}{16}-\frac{{{(y+1)}^{2}}}{9}=1\] Therefore, latus rectum = \[\frac{2{{b}^{2}}}{a}=2\times \frac{9}{4}=\frac{9}{2}\].


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