10th Class Mathematics Areas Related to Circles Question Bank Areas Related to Circles

  • question_answer
    The perimeter of a sector of a circle of radius \[5.2\text{ }cm\]is\[16.4\text{ }cm\]. The area of the sector is _____.                 

    A)  \[15.1\text{ }c{{m}^{2}}\]             

    B)  \[15.5\text{ }c{{m}^{2}}\]    

    C)                     \[15.6\,c{{m}^{2}}\]      

    D)         \[15.9\,c{{m}^{2}}\]    

    Correct Answer: C

    Solution :

    Perimeter of a sector of circle                         \[=\frac{\theta }{{{360}^{o}}}\times 2\pi r+2r\] \[\Rightarrow \]            \[\left( \frac{\theta }{{{360}^{o}}}\times 2\pi \times 5.2 \right)+(2\times 5.2)=16.4\] \[\Rightarrow \]            \[\frac{\theta }{{{360}^{o}}}\pi =\frac{16.4-10.4}{10.4}=\frac{6}{10.4}\] Area of sector of circle                       \[\frac{\theta }{{{360}^{o}}}\times \pi {{r}^{2}}=\frac{6}{10.4}\times {{(5.2)}^{2}}=15.6\,c{{m}^{2}}\]


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