Question

Radius and slant height of a solid cone are $20$ cm and $29$ cm respectively. Find its volume

Answer 1

Given, $r=20,l=29$
We know, $h=\sqrt{l^2-r^2}$

$=\sqrt{{29}^2-{20}^2}$

$=\sqrt{841-400}$

$=\sqrt{441}=21$
Volume of cone $=\frac{1}{3}\pi r^{2}h$ cubic unit
$=\frac{1}{3}\times \frac{22}{7}\times 20\times 20\times 21$
$=8800$ sq.cm.