CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2001

  • question_answer
    The value of\[\overrightarrow{a}.\{(\overrightarrow{b}\times \overrightarrow{c})\times (\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c})\}\]is equal to:

    A)  \[0\]                                    

    B)  \[[\overrightarrow{a}\,\,\overrightarrow{b}\,\,\overrightarrow{c}]\]

    C)  \[2\overrightarrow{a}\]                              

    D)         \[\overrightarrow{a}\]

    E)  none of these

    Correct Answer: A

    Solution :

    \[\overrightarrow{a}.[(\overrightarrow{b}\times \overrightarrow{c})\times (\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c})]\] \[=\overrightarrow{a}.[\overrightarrow{b}\times \overrightarrow{c}\times \overrightarrow{a}+\overrightarrow{b}\times \overrightarrow{c}\times \overrightarrow{b}+\overrightarrow{b}\times \overrightarrow{c}\times \overrightarrow{c}]\] \[=\overrightarrow{a}.[\overrightarrow{b}\times \overrightarrow{c}\times \overrightarrow{a}]=0\]


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