Question:
If the diameter of a cylinder is 28 cm and its height is 20 cm, then its curved surface area is
(a) 880 cm2
(b) 1760 cm2
(c) 3520 cm2
(d) 2640 cm2
Solution:
(b) $1760 \mathrm{~cm}^{2}$
Curved surface area of the cylinder $=2 \pi r h$
$=2 \times \frac{22}{7} \times 14 \times 20$
$=44 \times 40$
$=1760 \mathrm{~cm}^{2}$