Question

The volume of a cone of radius 7 $cm$ and slant height 14 $cm$ is ______.
$(use\pi =\frac{22}{7})$

• A. $622.381c{m}^3$
• B. $722.381c{m}^3$
• C. $618.381c{m}^3$
• D. $522.381c{m}^3$

Answer 1

The correct option is A $622.381c{m}^3$

Given,
Radius of the cone
$r=7cm$
Slant height of the cone
$l=14cm$

From the pythagoras theorem
$l^2=h^2$ + $r^2$,

height of the cone
$h=\sqrt{{14}^2-7^2}$
$h=\sqrt{147}=12.1243cm$

Volume of a Cone
$=\frac{1}{3}\times \pi \times r^{2}h$

$=\frac{1}{3}\times \frac{22}{7}\times 7^2\times 12.1243$

$=622.381c{m}^3$