JEE Main & Advanced Sample Paper JEE Main - Mock Test - 8

  • question_answer
    If \[\tan \theta +\sin \theta =m\] and \[\tan \theta -\sin \theta =n\], then

    A) \[{{m}^{2}}-{{n}^{2}}=4mn\]

    B) \[{{m}^{2}}+{{n}^{2}}=4mn\]

    C) \[{{m}^{2}}-{{n}^{2}}={{m}^{2}}+{{n}^{2}}\]

    D) \[{{m}^{2}}-{{n}^{2}}=4\sqrt{mn}\]

    Correct Answer: D

    Solution :

    [d]: Clearly, \[(m+n)=2tan\theta \] and \[(m-n)=2\sin \theta \] \[\therefore \]\[{{m}^{2}}-{{n}^{2}}=4\tan \theta .\sin \theta \]                          ...(i) Also,\[4\sqrt{mn}=4\sqrt{{{\tan }^{2}}\theta -{{\sin }^{2}}\theta }=4\sin \theta .tan\theta \]...(ii) From (i) and (ii), \[{{m}^{2}}-{{n}^{2}}=4\sqrt{mn}\]


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