JEE Main & Advanced Mathematics Conic Sections Question Bank Parabola

  • question_answer
    Equation of the parabola with its vertex at (1, 1) and focus (3, 1) is [Karnataka CET 2001, 02]

    A)            \[{{(x-1)}^{2}}=8(y-1)\]             

    B)            \[{{(y-1)}^{2}}=8(x-3)\]

    C)            \[{{(y-1)}^{2}}=8(x-1)\]             

    D)            \[{{(x-3)}^{2}}=8(y-1)\]

    Correct Answer: C

    Solution :

               Given, vertex of parabola (h, k) \[\equiv \] (1, 1) and its focus \[(a+h,\,k)\equiv \,(3,\,1)\] or \[a+h=3\] or \[a=2.\] We know that as the y-coordinates of vertex and focus are same, therefore axis of parabola is parallel to x-axis. Thus equation of the parabola is \[{{(y-\,k)}^{2}}=4a\,(x-h)\] or \[{{(y-1)}^{2}}\] \[=4\times 2(x-1)\] or \[{{(y-1)}^{2}}=8(x-1).\]


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