JEE Main & Advanced Mathematics Three Dimensional Geometry Question Bank Sphere

  • question_answer
    The centre of sphere passes through four points (0, 0, 0),    (0, 2, 0), (1, 0, 0) and (0, 0, 4) is [MP PET 2002]

    A)            \[\left( \frac{1}{2},\,1,\,2 \right)\]

    B)            \[\left( -\frac{1}{2},\,1,\,2 \right)\]

    C)            \[\left( \frac{1}{2},\,1,-\,2 \right)\]

    D)            \[\left( 1,\frac{1}{2},\,2 \right)\]

    Correct Answer: A

    Solution :

                       Let the equation of sphere            \[{{x}^{2}}+{{y}^{2}}+{{z}^{2}}+2ux+2vy+2wz+d=0\]            \[\because \] It passes through origin (0, 0, 0),            \ \[d=0\]            Also, it passes through (0, 2, 0)            \ \[4+4v=0\Rightarrow v=-1\]            Also, it passes through (1, 0, 0)            \ \[1+2u=0\Rightarrow u=-1/2\]            And it passes through (0, 0, 4)            \ \[16+8w\Rightarrow w=-2\]                    \ Centre \[(-u,\,-v,\,-w)=\left( \frac{1}{2},\,1,\,2 \right)\].


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