CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2010

  • question_answer
    The value of\[x\]in\[\left( 0,\frac{\pi }{2} \right)\]satisfying the equation \[\sin x\cos x=\frac{1}{4}\]is

    A)  \[\frac{\pi }{6}\]                                             

    B)  \[\frac{\pi }{3}\]

    C)  \[\frac{\pi }{8}\]                             

    D)         \[\frac{\pi }{4}\]

    E)  \[\frac{\pi }{12}\]

    Correct Answer: E

    Solution :

    We have \[\sin x\cos x=\frac{1}{4}\] \[\Rightarrow \]               \[\sin 2x=\frac{1}{2}\] \[\Rightarrow \]               \[\sin 2x=\sin \frac{\pi }{6}\] \[\Rightarrow \]               \[2x=nx+{{(-1)}^{n}}\frac{\pi }{6},n\in Z\] \[\Rightarrow \]               \[x=\frac{n\pi }{2}+{{(-1)}^{n}}\frac{\pi }{12},n\in z\] \[\Rightarrow \]               \[x=\frac{\pi }{12}\in \left( 0,\frac{\pi }{12} \right)for\,n=0\]


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