JEE Main & Advanced Sample Paper JEE Main Sample Paper-46

  • question_answer
    Direction: Let a, b and c be three vectors such that \[|a|\,=\,|b|\,=\,|\,c|\,=4\]and the angle between a and b is \[\pi /3,\] the angle between b and c is \[\pi /3,\] and angle between c and a is \[\pi /3,\]. Then,
    The height of the parallelepiped whose adjacent edges are represented by the vectors a, b and c is

    A)  \[4\sqrt{\frac{2}{3}}\]                      

    B)  \[3\sqrt{\frac{2}{3}}\]

    C)  \[4\sqrt{\frac{3}{2}}\]                      

    D)  \[3\sqrt{\frac{3}{2}}\]

    Correct Answer: A

    Solution :

     Volume of the parallel piped = (base area) \[\times \] high \[\Rightarrow \]            \[32\sqrt{2}=2\times \left( \frac{1}{2}\times 4\times 4\times \sin \,\frac{\pi }{3} \right)\times h\] \[\Rightarrow \]            \[h=4\sqrt{\frac{2}{3}}\]


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