Question:
The diameter of a cylinder is 28 cm and its height is 20 cm. The total surface area of the cylinder is
(a) 2993 cm2
(b) 2992 cm2
(c) 2292 cm2
(d) 2229 cm2
Solution:
(b) 2992 cm2
The total surface area of the cylinder $=2 \pi r+2 r^{2}$
$=2 \pi r(h+r)$
$=\left[2 \times \frac{22}{7} \times 14 \times(20+14)\right] \mathrm{cm}^{2} \quad\left[d=28 \mathrm{~cm} \Rightarrow r=\frac{28}{2} \mathrm{~cm}=14 \mathrm{~cm}\right]$
$=\frac{20944}{7} \mathrm{~cm}^{2}$
$=2992 \mathrm{~cm}^{2}$