CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2004

  • question_answer
    The projection of \[\vec{a}=2\,\hat{i}+3\,\hat{j}-2\hat{k}\] on\[\vec{b}=\,\hat{i}+2\,\hat{j}+3\hat{k}\] is :

    A)  \[\frac{1}{\sqrt{14}}\]                  

    B)  \[\frac{2}{\sqrt{14}}\]

    C)  \[\sqrt{14}\]                                     

    D)  \[\frac{-2}{\sqrt{14}}\]

    Correct Answer: B

    Solution :

    Here,                                     \[\overrightarrow{a}=2\,\hat{i}\,+3\,\hat{j}-2\,\hat{k}\] and \[\overrightarrow{b}=\hat{i}+2\hat{j}+3\,\hat{k}\] \[\therefore \] Projection of \[\overrightarrow{a}=2\hat{i}+3\hat{j}-3\,\hat{k}\] on \[\overrightarrow{b}=\hat{i}+2\hat{j}+3\hat{k}\] is                 \[=\frac{\overrightarrow{a}\,.\,\,\overrightarrow{b}}{|\overrightarrow{b}|}\]                 \[=\frac{2\times 1+3\times 2-2\times 3}{\sqrt{{{1}^{2}}+{{2}^{2}}+{{3}^{2}}}}\]                 \[=\frac{2}{\sqrt{14}}\]


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