JEE Main & Advanced Mathematics Vector Algebra Question Bank Modulus of vector Algebra of vectors

  • question_answer
    If the position vectors of the point A, B, C be i, j, k respectively and P be a point such that \[\overrightarrow{AB}=\overrightarrow{CP},\] then the position vector of P is

    A) \[-\mathbf{i}+\mathbf{j}+\mathbf{k}\]           

    B) \[-\mathbf{i}-\mathbf{j}+\mathbf{k}\]

    C) \[\mathbf{i}+\mathbf{j}-\mathbf{k}\]               

    D) None of these

    Correct Answer: A

    Solution :

    Let the position vector of P is \[x\mathbf{i}+y\mathbf{j}+z\mathbf{k},\] then \[\overrightarrow{AB}=\overrightarrow{CP}\Rightarrow \mathbf{j}-\mathbf{i}=x\mathbf{i}+y\mathbf{j}+(z-1)\mathbf{k}\] By comparing the coefficients of \[\mathbf{i},\,\,\mathbf{j}\] and \[\mathbf{k},\]we get \[x=-1,\]  \[y=1\,\text{and}\,\text{z--1}=\text{0}\Rightarrow z=1\] Hence required position vector is \[-\mathbf{i}+\mathbf{j}+\mathbf{k}.\]


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