JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Mock Test - Trigonometric Functions

  • question_answer
    The least positive solution of \[\cot \left( \frac{\pi }{3\sqrt{3}}\sin 2x \right)=\sqrt{3}\]lies in

    A) \[\left( 0,\frac{\pi }{6} \right]\]     

    B) \[\left( \frac{\pi }{9},\frac{\pi }{6} \right)\]

    C) \[\left( \frac{\pi }{12},\frac{\pi }{9} \right]\]         

    D) \[\left( \frac{\pi }{3},\frac{\pi }{2} \right]\]

    Correct Answer: A

    Solution :

    [a] \[\cot \left( \frac{\pi }{3\sqrt{3}}\sin 2x \right)=\sqrt{3}\] \[\Rightarrow \,\frac{\pi }{3\sqrt{3}}\sin 2x=n\pi +\frac{\pi }{6},n\in Z\] \[\Rightarrow \,\sin 2x=3\sqrt{3}n+\frac{\sqrt{3}}{2}\] For least positive solution, n=0 \[\Rightarrow \sin 2x=\frac{\sqrt{3}}{2}\] \[\Rightarrow 2x=\frac{\pi }{3}\Rightarrow x=\frac{\pi }{6}\]


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