A) \[154\,\,c{{m}^{2}}\]
B) \[77\,\,c{{m}^{2}}\]
C) \[44\,\,c{{m}^{2}}\]
D) \[22\,\,c{{m}^{2}}\]
Correct Answer: B
Solution :
The length of wire = Perimeter of tha square \[=4\times \sqrt{\text{Area}\,\,\text{of}\,\text{square}}=4\times \sqrt{81}=4\times 9=36\,cm\]Now, perimeter of semi-circular shape = 36 cm \[\Rightarrow \] \[(\pi \times r+2r)=36\,\,cm\] \[\Rightarrow \] \[r\left( \frac{22}{7}+2 \right)=36\,\,cm\] \[\Rightarrow \]\[r\times \frac{36}{7}=36\,\,cm\]\[\Rightarrow \]\[r=\frac{36\times 7}{36}=7\,\,cm\] \[\therefore \]Required area \[=\frac{\pi {{r}^{2}}}{2}=\frac{22\times 7\times 7}{7\times 2}=77\,\,c{{m}^{2}}\]You need to login to perform this action.
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