RAJASTHAN ­ PET Rajasthan PET Solved Paper-2007

  • question_answer
    If\[y=ax+p\]is a tangent to the hyperbola \[\frac{{{x}^{2}}}{{{a}^{2}}}-\frac{{{y}^{2}}}{{{b}^{2}}}=1,\]then the locus of the point \[P(\alpha ,\beta )\]or is

    A)  an ellipse         

    B)  a circle

    C)  a parabola        

    D)  a hyperbola

    Correct Answer: D

    Solution :

     Line\[y=mx+c\]will be a tangent to hyperbola \[\frac{{{x}^{2}}}{{{a}^{2}}}-\frac{{{y}^{2}}}{{{b}^{2}}}=1.\]If \[{{c}^{2}}={{a}^{2}}{{m}^{2}}-{{b}^{2}}\] Similarly, line\[y=ax+\beta \] will be tangent, if \[{{\beta }^{2}}={{\alpha }^{2}}{{a}^{2}}-{{b}^{2}}\] \[\therefore \] Locus of\[(\alpha ,\beta )\]is \[{{y}^{2}}={{a}^{2}}{{x}^{2}}-{{b}^{2}}\] \[\Rightarrow \] \[{{a}^{2}}{{x}^{2}}-{{y}^{2}}-{{b}^{2}}=0\] Since, this equation represent a hyperbola. \[\therefore \] Locus of\[P(\alpha ,\beta )\]is a hyperbola.


You need to login to perform this action.
You will be redirected in 3 sec spinner