RAJASTHAN ­ PET Rajasthan PET Solved Paper-2005

  • question_answer
    If in the interval\[\left[ 0,\frac{\pi }{2} \right]\]the area of the region bounded by the curve\[y=sin\text{ }x\]and\[x-\]axis is A sq unit, then in the same interval, the area of the region bounded by the curve\[y=cos\text{ }x\] and\[x-\]axis is

    A)  A sq unit         

    B) \[\frac{\pi }{2}-A\] sq unit

    C)  \[-A\] sq unit       

    D)  None of these

    Correct Answer: A

    Solution :

     Given, \[\int_{0}^{\pi /2}{\sin xdx=A}\]              ...(i) Now, \[\int_{0}^{\pi /2}{\cos xdx}\] \[=\int_{0}^{\pi /2}{\cos \left( \frac{\pi }{2}-x \right)dx}\] \[=\int_{0}^{\pi /2}{(\sin x)dx}\] \[=\int_{0}^{\pi /2}{\sin xdx}\] \[=A\] [from Eq.(i)]


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