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JEE Main & Advanced Mathematics Vector Algebra Question Bank Modulus of vector Algebra of vectors

  • question_answer
    The perimeter of a triangle with sides \[3\mathbf{i}+4\mathbf{j}+5\mathbf{k},\,\] \[4\mathbf{i}-3\mathbf{j}-5\mathbf{k}\] and \[7\mathbf{i}+\mathbf{j}\] is                                                [MP PET 1991]

    A) \[\sqrt{450}\]

    B) \[\sqrt{150}\]

    C) \[\sqrt{50}\]          

    D) \[\sqrt{200}\]

    Correct Answer: A

    Solution :

    \[{{l}_{1}}=\sqrt{25+25}=5\sqrt{2},\] \[{{l}_{2}}=\sqrt{25+25}=5\sqrt{2}\],\[{{l}_{3}}=5\sqrt{2}.\] Hence, \[{{l}_{1}}+{{l}_{2}}+{{l}_{3}}=3\sqrt{50}=\sqrt{450}.\]    


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