A) \[2\pi l({{r}^{2}}-{{l}^{2}})\]
B) \[2\pi rl\left( \frac{1}{2r}+1 \right)\]
C) \[2\pi l({{r}^{2}}+{{t}^{2}})\]
D) \[2\pi l(r+{{t}^{2}})\]
Correct Answer: B
Solution :
Required volume \[=\pi \,\,{{(r+t)}^{2}}\,l-\pi {{r}^{2}}l\] \[=\pi \,l\,(2rt+{{t}^{2}})\] \[=2\,\pi \,r\,lt\left( \frac{t}{2r}+1 \right)\]You need to login to perform this action.
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