A) \[4:13\]
B) \[2:5\]
C) \[6:13\]
D) \[9:13\]
Correct Answer: B
Solution :
Area of shaded region \[=\left( \frac{1}{2}\pi \times {{6}^{2}}-\frac{1}{2}\pi \times {{4}^{2}} \right)\] \[=\frac{1}{2}\times \left( 36-18 \right)=\frac{20\pi }{2}=10\pi \] Radius of bigger circle\[=\frac{12}{2}=6\,\,cm\] Now, Area of unshaded \[=\frac{1}{2}\times \pi \times {{6}^{2}}+\frac{1}{2}\times \pi \times {{4}^{2}}\] \[=\frac{1}{2}\pi \left( 36+14 \right)=\frac{1}{2}\pi \times 50=25\pi \] Ratio\[=\frac{10\pi }{25\pi }=\frac{2}{5}=2:5\]You need to login to perform this action.
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