CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2002

  • question_answer
    If \[{{\cos }^{-1}}\sqrt{p}+{{\cos }^{-1}}\sqrt{1-p}+{{\cos }^{-1}}\sqrt{1-q}\]\[=\frac{3\pi }{4}\] then the value of \[q\] is:

    A)  \[2/\sqrt{2}\]                   

    B)  \[1\]

    C)  \[1/2\]                                

    D)  \[1/3\]

    Correct Answer: C

    Solution :

    \[{{\cos }^{-1}}\sqrt{p}+{{\cos }^{-1}}\sqrt{1-p}+{{\cos }^{-1}}\sqrt{1-q}=\frac{3\pi }{4}\] \[{{\cos }^{-1}}\sqrt{p}+{{\sin }^{-1}}\sqrt{p}+{{\cos }^{-1}}\sqrt{1-q}=\frac{3\pi }{4}\] \[\frac{\pi }{2}+{{\cos }^{-1}}\sqrt{1-q}=\frac{3\pi }{4}\] \[{{\cos }^{-1}}\sqrt{1-q}=\frac{3\pi }{4}-\frac{\pi }{2}=\frac{3\pi -2\pi }{4}=\frac{\pi }{4}\] \[\sqrt{1-q}=1/\sqrt{2}\Rightarrow 1-q=1/2\Rightarrow q=1/2.\]


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