Question

find $ell$. $ell=sqrt{?}\text{ ft}$

Explanation:

Step1: Apply Pythagorean theorem

For a cone, the slant - height $\ell$, the height $h$ and the radius $r$ are related by $\ell=\sqrt{h^{2}+r^{2}}$. Here, $h = 9$ ft and $r = 8$ ft.

Step2: Calculate $h^{2}+r^{2}$

$h^{2}=9^{2}=81$ and $r^{2}=8^{2}=64$. Then $h^{2}+r^{2}=81 + 64$.
$h^{2}+r^{2}=145$.

Answer:

$\sqrt{145}$ ft