Question

A solid right circular cylinder has radius $7cm$ and height $20cm$. Find its (i) curved surface area and (ii) total surface area. (Take $\pi =\frac{22}{7}$)

Answer 1

Let $r$ and $h$ be the radius and height of the solid right circular cylinder respectively
Given that $r=7cm$ and $h=20cm$
Curved surface area, $CSA=2\pi rh$
$=2\times \frac{22}{7}\times 7\times 20$
Thus,the curved surface area $=880sq.cm$
Now, the total surface area $=\pi r[h+r]$
$=2\times \frac{22}{7}\times 7\times [20+7]=44\times 27$
Thus, the total surface are $=1188sq.cm$