CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2008

  • question_answer
    The projection of \[\vec{a}=3\hat{i}-\hat{j}+5\hat{k}\] on \[\vec{b}=2\hat{i}+3\hat{j}+\hat{k}\]is

    A)  \[\frac{8}{\sqrt{35}}\]                  

    B)  \[\frac{8}{\sqrt{39}}\]

    C)  \[\frac{8}{\sqrt{14}}\]                  

    D)  \[\sqrt{14}\]

    Correct Answer: C

    Solution :

    Given,   \[\vec{a}=3\hat{i}-\hat{j}+5\hat{k}\] and \[\vec{b}=2\hat{i}+3\hat{j}+\hat{k}\] The projection of \[\vec{a}\] on \[\vec{b}=\frac{\vec{a}.\vec{b}}{|\vec{b}|}\]                 \[=\frac{(3\hat{i}-\hat{j}+5\hat{k}).(2\hat{i}+3\hat{j}+\hat{k})}{\sqrt{{{2}^{2}}+{{3}^{2}}+{{1}^{2}}}}\]                 \[=\frac{6-3+5}{\sqrt{14}}=\frac{8}{\sqrt{14}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner