A) 710.29
B) 757.43
C) 355.14
D) 908.91
Correct Answer: B
Solution :
Total surface area \[=2\pi R_{1}^{2}+2\pi R_{2}^{2}+\pi \left( R_{2}^{2}-R_{1}^{2} \right)\] Where \[{{R}_{2}}=\]ex-radius \[{{R}_{1}}=\]in-radius \[=2\pi \left( R_{1}^{2}+R_{2}^{2} \right)+\pi \left( R_{2}^{2}-R_{1}^{2} \right)\] \[=2\times \frac{22}{7}({{7}^{2}}+{{8}^{2}})+\frac{22}{7}({{8}^{2}}-{{7}^{2}})\] \[=2\times \frac{22}{7}\times (49+64)+\frac{22}{7}\times 15\] \[=\frac{44}{7}\times 113+\frac{22}{7}\times 15\] \[=\frac{22}{7}(226+15)\] \[=\frac{22}{7}\times 241=757.43\]sq. cm.
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