NEET Sample Paper NEET Sample Test Paper-12

  • question_answer
    If \[\left| \vec{A}\times \vec{B} \right|=\sqrt{3}\vec{A}.\vec{B},\]then the value of \[\left| \vec{A}+\vec{B} \right|\]is:

    A) \[{{({{A}^{2}}+{{B}^{2}}+AB)}^{1/2}}\]

    B)  \[{{\left( {{A}^{2}}+{{B}^{2}}+\frac{AB}{\sqrt{3}} \right)}^{1/2}}\]

    C) \[A+B\]

    D) \[{{\left( {{A}^{2}}+{{B}^{2}}+\sqrt{3}AB \right)}^{1/2}}\]

    Correct Answer: C

    Solution :

    \[\vec{p}=\]vector sum\[=\vec{A}+\vec{B}\] \[\vec{Q}=\]vector differences \[=\vec{A}+\vec{B}\] Since \[\vec{P}\]and \[\vec{Q}\]are perpendicular to \[\vec{P}.\vec{Q}=0\] \[\Rightarrow \]\[(\vec{A}+\vec{B}).(\vec{A}-\vec{B})=0\] \[\Rightarrow \]\[{{A}^{2}}={{B}^{2}}\Rightarrow \left| {\vec{A}} \right|=\left| {\vec{B}} \right|\]


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