| The radius of a right circular cone is 3 cm and its height is 4 cm. The total surface area of the cone is [SSC (CPO) 2014] |
A) \[48.4\,\,c{{m}^{2}}\]
B) \[64.4\,\,c{{m}^{2}}\]
C) \[96.4\,\,c{{m}^{2}}\]
D) \[75.4\,\,c{{m}^{2}}\]
Correct Answer: D
Solution :
| Given, radius of cone \[r=3\,\,cm\] |
| height of cone \[h=4\,\,cm\] |
 |
| Slant height \[l=\sqrt{{{r}^{2}}+{{h}^{2}}}\] |
| \[=\sqrt{{{3}^{2}}+{{4}^{2}}}=\sqrt{25}=5\,\,cm\] |
| \[\therefore \]Total surface area of cone \[=\pi r\,\,(l+r)\] |
| \[=3.14\times 3\,\,(5+3)\] |
| \[=3.14\times 24=75.36\,\,c{{m}^{2}}\] |
| \[=75.4\,\,c{{m}^{2}}\] |
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