JEE Main & Advanced Mathematics Conic Sections Question Bank Hyperbola

  • question_answer
    The equation of the hyperbola in the standard form (with transverse axis along the x-axis) having the length of the latus rectum = 9 units and eccentricity = 5/4 is [Kerala (Engg.) 2005]

    A)            \[\frac{{{x}^{2}}}{16}-\frac{{{y}^{2}}}{18}=1\]                            

    B)            \[\frac{{{x}^{2}}}{36}-\frac{{{y}^{2}}}{27}=1\]

    C)            \[\frac{{{x}^{2}}}{64}-\frac{{{y}^{2}}}{36}=1\]                            

    D)            \[\frac{{{x}^{2}}}{36}-\frac{{{y}^{2}}}{64}=1\]

    E)            \[\frac{{{x}^{2}}}{16}-\frac{{{y}^{2}}}{9}=1\]

    Correct Answer: C

    Solution :

                      \[\because \frac{2{{b}^{2}}}{{{a}^{2}}}=9\] Þ \[2{{b}^{2}}=9a\]                              ?..(i)                         Now \[{{b}^{2}}={{a}^{2}}({{e}^{2}}-1)=\frac{9}{16}{{a}^{2}}\]Þ\[a=\frac{4}{3}b\]?..(ii), (\[\because \]\[e=\frac{5}{4}\])                    From (i) and (ii), \[b=6\], \[a=8\]                    Hence, equation of hyperbola\[\frac{{{x}^{2}}}{64}-\frac{{{y}^{2}}}{36}=1\].


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