RAJASTHAN ­ PET Rajasthan PET Solved Paper-2001

  • question_answer
    \[\overrightarrow{a}[\overrightarrow{a}\times (\overrightarrow{a}\times \overrightarrow{b})]\]is equal to

    A)  \[(\overrightarrow{a}.\overrightarrow{a})(\overrightarrow{a}\times \overrightarrow{b})\]

    B)  \[(\overrightarrow{a}.\overrightarrow{a})(\overrightarrow{b}\times \overrightarrow{a})\]

    C)  \[(\overrightarrow{b}.\overrightarrow{b})(\overrightarrow{a}\times \overrightarrow{b})\]

    D)  \[(\overrightarrow{b}.\overrightarrow{b})(\overrightarrow{b}\times \overrightarrow{a})\]

    Correct Answer: B

    Solution :

     \[\overrightarrow{a}\times [\overrightarrow{a}\times (\overrightarrow{a}\times \overrightarrow{b})]=\overrightarrow{a}\times [(\overrightarrow{a}.\overrightarrow{b})\overrightarrow{a}-(\overrightarrow{a}.\overrightarrow{a})\overrightarrow{b}]\] \[=-(\overrightarrow{a}.\overrightarrow{a})(\overrightarrow{a}\times \overrightarrow{b})\] \[=(\overrightarrow{a}.\overrightarrow{a})(\overrightarrow{b}\times \overrightarrow{a})\]


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