| What is the approximate total surface area of a right circular cone of height 14 cm and base radius 7 cm [NICL (AO) 2014] |
A) 510
B) 511
C) 490
D) 505
E) 499
Correct Answer: E
Solution :
| Height of cone, h =14 cm |
| Radius of cone, r = 7 cm |
| \[\therefore \] Slant height, \[l=\sqrt{{{h}^{2}}+{{r}^{2}}}=\sqrt{{{14}^{2}}+{{7}^{2}}}\] |
| \[=\sqrt{196+49}=\sqrt{245}\approx 15.65\] |
| So, total surface area of cone |
| \[=\pi r\,(l+r)=\frac{22}{7}\times 7\,(15.65+7)\approx 499\] |
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