BCECE Engineering BCECE Engineering Solved Paper-2013

  • question_answer
    The area bounded by the curve\[y=\sin x\]between \[x=0\]and \[x=2\pi \]is

    A)  1 sq unit             

    B)         2 sq units           

    C)         4 sq units            

    D)          8 sq units

    Correct Answer: C

    Solution :

    The graph of \[y=\sin x\]can be drawn as required area = Area of OABO + Area BCDB \[=\int\limits_{0}^{x}{|\sin \,x|dx+\int\limits_{\pi }^{2\pi }{|\sin \,x|}dx}\]                 \[=\int\limits_{0}^{x}{\sin x\,dx+\int\limits_{\pi }^{2\pi }{(-\sin \,x)dx}}\] (\[\because \,sin\ge 0\,\]for \[x\in [x,\pi ]\] and \[\sin x\le 0\]for \[x\in [{{\pi }_{1}}2\pi ]\])                 \[=[-\cos x]_{0}^{\pi }+[\cos x]_{\pi }^{2\pi }\] \[=-\cos \pi +\cos 0+cos2\pi -\cos \pi \] \[=-(-1)+1+1-(-1)\] \[\text{=}\,\text{4sq}\,\text{units}\]


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