The radii of the circular ends of a solid frustum of a cone are 33 cm and 27 cm and its slant height is 10 cm.
Question:
The radii of the circular ends of a solid frustum of a cone are $33 \mathrm{~cm}$ and $27 \mathrm{~cm}$ and its slant height is $10 \mathrm{~cm}$. Find its total surface area. [Use $\pi=3.14 .$ ]
Solution:
Greater radius = R = 33 cm
Smaller radius = r = 27 cm
Slant height = l = 10 cm
Surface area of the frustum
$=\pi R^{2}+\pi r^{2}+\pi l(R+r)$
$=\pi\left[R^{2}+r^{2}+l(R+r)\right]$
$=\left[33^{2}+27^{2}+10(33+27)\right] \pi$
$=[1089+729+10(60)] \pi$
$=2418 \times 3.14$
$=7592.52 \mathrm{~cm}^{2}$