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

  • question_answer
    The value of the expression \[{{\sin }^{-1}}\left( \sin \frac{22\pi }{7} \right)\]\[{{\cos }^{-1}}\left( \cos \frac{5\pi }{3} \right)\]+\[{{\tan }^{-1}}\left( \tan \frac{5\pi }{3} \right)\]+\[{{\sin }^{-1}}(cos2)\]is

    A) \[\frac{17\pi }{42}-2\]

    B) \[-\,2\]

    C) \[\frac{-\pi }{21}-2\]      

    D) none of these

    Correct Answer: A

    Solution :

    [a] \[{{\sin }^{-1}}\sin \left( \frac{22\pi }{7} \right)={{\sin }^{-1}}\sin \left( 3\pi +\frac{\pi }{7} \right)=-\frac{\pi }{7}\] \[{{\cos }^{-1}}\cos \left( \frac{5\pi }{3} \right)={{\cos }^{-1}}\cos \left( 2\pi -\frac{\pi }{3} \right)=\frac{\pi }{3}\] \[{{\tan }^{-1}}\tan \left( \frac{5\pi }{7} \right)={{\tan }^{-1}}\tan \left( \pi -\frac{2\pi }{7} \right)=-\frac{2\pi }{7}\]\[{{\sin }^{-1}}\cos (2)=\frac{\pi }{2}-{{\cos }^{-1}}\cos 2=\frac{\pi }{2}-2\] \[\therefore \]Required value\[=-\frac{\pi }{7}+\frac{\pi }{3}-\frac{2\pi }{7}+\frac{\pi }{2}-2\] \[=\frac{(-18+35)\pi }{42}-2\] \[=\frac{17\pi }{42}-2\]


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