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NEET Sample Paper NEET Sample Test Paper-18

  • question_answer
    Two vectors\[\vec{A}\]and\[\vec{B}\] are such that \[|\vec{A}+\vec{B}|=|\vec{A}-\vec{B}|.\] Then angle between the vectors A and B is

    A) \[0{}^\circ \]                            

    B) \[60{}^\circ \]

    C) \[90{}^\circ \]

    D) \[180{}^\circ \]

    Correct Answer: C

    Solution :

    As \[|\vec{A}+\vec{B}|\,=\,|\vec{A}-\vec{B}|\] so \[{{A}^{2}}+{{B}^{2}}+2AB\cos \theta ={{A}^{2}}+{{B}^{2}}-2AB\cos \theta \] or \[4AB\cos \theta =0\]or \[\cos \theta =\text{i}\text{.e}\text{.}={{90}^{o}}.\] Hence, the correction option is [c].


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