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JEE Main & Advanced Mathematics Vector Algebra Question Bank Scaler or Dot product of two vectors and its application

  • question_answer
    If the angle between two vectors \[\mathbf{i}+\mathbf{k}\] and \[\mathbf{i}-\mathbf{j}+a\mathbf{k}\] is \[\pi /3,\] then the value of \[a=\]                            [MP PET 1997]

    A)             2

    B)             4

    C)             ? 2

    D)             0

    Correct Answer: D

    Solution :

                    \[\cos \frac{\pi }{3}=\frac{1+a}{\sqrt{2}\sqrt{2+{{a}^{2}}}}\Rightarrow a=0\].


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