RAJASTHAN ­ PET Rajasthan PET Solved Paper-2003

  • question_answer
    Equation   of  tangent   to  the   ellipse \[{{x}^{2}}+16{{y}^{2}}=16\]which makes an angle of\[60{}^\circ \]with\[x-\]axis, is

    A)  \[\sqrt{3}x-y+7=0\]   

    B)  \[\sqrt{3}x-y-7=0\]

    C)  \[\sqrt{3}x-y\pm 7=0\]   

    D)  None of these

    Correct Answer: A

    Solution :

     Given, \[m=\tan 60{}^\circ =\sqrt{3}\] Also ellipse, \[{{x}^{2}}+16{{y}^{2}}=16\] \[\Rightarrow \] \[\frac{{{x}^{2}}}{16}+\frac{{{y}^{2}}}{1}=1\] Here,      \[{{a}^{2}}=16,{{b}^{2}}=1\] \[\therefore \]Equation of tangent \[y=\sqrt{3}x\pm \sqrt{16.3+1}\] [From\[y=mx\pm \sqrt{{{a}^{2}}{{m}^{2}}+{{b}^{2}}}\]] \[\Rightarrow \] \[y=\sqrt{3}x\pm \sqrt{49}\] \[\Rightarrow \] \[y=\sqrt{3}x\pm 7\] Hence, required equation is\[\sqrt{3}x-y\pm 7=0\]


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