CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    \[\int_{-1/2}^{1/2}{\frac{dx}{{{(1-{{x}^{2}})}^{1/2}}}}\]is equal to:

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

    B)  \[\frac{\pi }{4}\]                             

    C)  \[\frac{\pi }{2}\]                             

    D)         0

    E)  \[\frac{\pi }{3}\]          

    Correct Answer: E

    Solution :

    Let \[I=\int_{-1/2}^{1/2}{\frac{dx}{{{(1-{{x}^{2}})}^{1/2}}}}\] Again let\[f(x)=\frac{1}{{{(1-{{x}^{2}})}^{1/2}}}\]                 \[f(-x)=\frac{1}{{{(1-{{x}^{2}})}^{1/2}}}=f(x)\] \[\therefore \]  \[I=2\int_{0}^{1/2}{\frac{dx}{{{(1-{{x}^{2}})}^{1/2}}}}\]                 \[=\left( 2{{\sin }^{-1}}\frac{x}{1} \right)_{0}^{1/2}\]                                             \[=2{{\sin }^{-1}}\frac{1}{2}=2\times \frac{\pi }{6}=\frac{\pi }{3}\]


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