CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2006

  • question_answer
    The equation of the hyperbola whose vertices are at (5, 0) and\[(-\text{ }5,0)\]and one of the  directrices is\[x=\frac{25}{7},\]is:

    A)  \[\frac{{{x}^{2}}}{25}-\frac{{{y}^{2}}}{24}=1\]                   

    B)  \[\frac{{{x}^{2}}}{24}-\frac{{{y}^{2}}}{25}=1\]

    C)  \[\frac{{{x}^{2}}}{16}-\frac{{{y}^{2}}}{25}=1\]   

    D)         \[\frac{{{x}^{2}}}{25}-\frac{{{y}^{2}}}{16}=1\]

    E)  \[\frac{{{x}^{2}}}{25}-\frac{{{y}^{2}}}{24}=-1\]

    Correct Answer: A

    Solution :

    Vertices of hyperbola are\[(a,0),(-a,0)\] Given vertices\[(5,0),\text{ }(-5,0)\] \[\therefore \]  \[a=5\] Also one of the directrix let \[x=\frac{a}{e}\]is given as      \[x=\frac{25}{7}\] \[\Rightarrow \]               \[e=\frac{7}{5}\] \[\therefore \]  \[{{b}^{2}}={{a}^{2}}({{e}^{2}}-1)=25\left( \frac{49}{25}-1 \right)=24\] \[\therefore \] Equation hyperbola is                 \[\frac{{{x}^{2}}}{25}-\frac{{{y}^{2}}}{24}=1\]


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