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

  • question_answer
    If \[\alpha \in \left( -\frac{3\pi }{2},-\pi  \right)\]then the value of \[{{\tan }^{-1}}(cot\alpha )\]-\[{{\cot }^{-1}}(tan\alpha )+si{{n}^{-1}}(sin\alpha )+co{{s}^{-1}}(cos\alpha )\]is equal to

    A) \[2\pi +a\]        

    B) \[\pi +a\]

    C) 0                     

    D) \[\pi -a\]

    Correct Answer: C

    Solution :

    [c] For \[\alpha \in \left( -\frac{3\pi }{2},-\pi  \right),\tan \alpha <0\] \[\Rightarrow {{\tan }^{-1}}(cot\alpha )-co{{t}^{-1}}(tan\alpha )\times \] \[{{\tan }^{-1}}(cot\alpha )-\left[ \frac{\pi }{2}-{{\tan }^{-1}}(tan\alpha ) \right]\] \[={{\tan }^{-1}}(cot\alpha )+{{\tan }^{-1}}(tan\alpha )-\frac{\pi }{2}\] \[=-\pi \] Also for points in the second quadrant, we have \[{{\sin }^{-1}}(\sin \alpha )+{{\cos }^{-1}}(cos\alpha )=\pi \]


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