A) \[402.12\,c{{m}^{2}}\]
B) \[298\,c{{m}^{2}}\]
C) \[377.14\,c{{m}^{2}}\]
D) \[315\,c{{m}^{2}}\]
Correct Answer: C
Solution :
Since, \[\Delta \text{ }OAB\tilde{\ }\Delta \text{ }OCD\] \[\frac{AB}{CD}=\frac{OB}{OD}\] \[\Rightarrow \] \[\frac{9}{CD}=\frac{12}{4}\] \[\Rightarrow \] \[CD=\frac{9\times 4}{12}\] \[\Rightarrow \] \[CD=3\,cm\] Slant height of cone \[(l)=\sqrt{{{12}^{2}}+{{9}^{2}}}=15cm\] Curved surface area of cone \[=\pi rl=135\,\pi \] Slant height of conical part containing water \[({{l}_{1}})=\sqrt{{{4}^{2}}+{{3}^{2}}}=5\,cm\] Curved surface area of conical part containing water \[=\pi {{r}_{1}}{{l}_{1}}=15\pi \] Surface area of cone not in contact with water \[=135\pi -15\pi =377.14c{{m}^{2}}\]You need to login to perform this action.
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