Question

Find the area of metal sheet required in making a closed hollow cone of base radius $7$ cm and height $24$ cm.

Answer 1

Here,

$h=24cm$ and $r=7cm$

$l=\sqrt{r^2+h^2}$

$l=\sqrt{7^2+{24}^2}$

$l=\sqrt{49+576}$

$l=\sqrt{625}$

$\therefore$ $l=25$

Total surface area of cone $=\pi r(l+r)$

$=\frac{22}{7}\times 7(25+7)$

$=22\times 32$

$=704c{m}^2$

$\therefore$ The total area of the metal sheet required to make the hollow cone is $704c{m}^2.$