BCECE Engineering BCECE Engineering Solved Paper-2006

  • question_answer
    If\[4{{\sin }^{-1}}x+{{\cos }^{-1}}x=\pi ,\] then \[x\]is equal to:

    A)  0                                            

    B)  1/2                       

    C)  \[-1/2\]                              

    D)  1

    Correct Answer: B

    Solution :

    Given, \[4{{\sin }^{-1}}x+{{\cos }^{-1}}x=\pi \] \[\Rightarrow \]               \[4{{\sin }^{-1}}x+\frac{\pi }{2}-{{\sin }^{-1}}x=\pi \]                 \[\left( \because \,{{\cos }^{-1}}x+{{\sin }^{-1}}x=\frac{\pi }{2} \right)\]                 \[\Rightarrow \]               \[3{{\sin }^{-1}}x=\pi -\frac{\pi }{2}\]                 \[\Rightarrow \]               \[3{{\sin }^{-1}}x=\frac{\pi }{2}\] \[\Rightarrow \]               \[x=\sin \frac{\pi }{6}\] \[\Rightarrow \]               \[x=\frac{1}{2}\]


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