RAJASTHAN ­ PET Rajasthan PET Solved Paper-2007

  • question_answer
    Let the coordinates of P are (1,0) and point Q lies on the curve\[{{y}^{2}}=8x\]. The locus of the midpoint of PQ is

    A)  \[{{y}^{2}}-4x+2=0\]

    B) \[{{y}^{2}}+4x+2=0\]

    C)  \[{{x}^{2}}+4y+2=0\]    

    D)  \[{{x}^{2}}-4y+2=0\]

    Correct Answer: A

    Solution :

     Coordinates of P are (1, 0). Let the coordinates of the point Q are\[(2{{t}^{2}},4t)\]and mid-point of PQ is\[(h,k),\] Then,          \[2h=2{{t}^{2}}+1\] and        \[2k=4t\Rightarrow t=\frac{k}{2}\] \[\therefore \] \[2h=\frac{2{{k}^{2}}}{4}+1\] \[\Rightarrow \] \[4h={{k}^{2}}+2\] \[\therefore \]Locus of\[(h,k)\]is \[{{y}^{2}}-4x+2=0\]


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