RAJASTHAN ­ PET Rajasthan PET Solved Paper-2008

  • question_answer
    The equations of tangent to the ellipse \[\frac{{{x}^{2}}}{{{a}^{2}}}+\frac{{{y}^{2}}}{{{b}^{2}}}=1\]which cut equal intercepts from the axes, are

    A)  \[y=\sqrt{3}x\pm \sqrt{3{{a}^{2}}+{{b}^{2}}}\]

    B)  \[y=\pm x+\sqrt{{{a}^{2}}+{{b}^{2}}}\]

    C)  \[y=\sqrt{3x}\pm +\sqrt{{{a}^{2}}+3{{b}^{2}}}\]

    D)  None of the above

    Correct Answer: B

    Solution :

     Let equations of line which cut equal intercepts are \[y\pm x=\pm c\] or            \[y=\pm \text{ }x\pm c\] Since, it is a tangent of the ellipse \[\frac{{{x}^{2}}}{{{a}^{2}}}+\frac{{{y}^{2}}}{{{b}^{2}}}=1\] \[\therefore \] \[c=\sqrt{{{a}^{2}}+{{b}^{2}}}\] Hence, required equation of line is \[y=\pm x+\sqrt{{{a}^{2}}+{{b}^{2}}}\]


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