# What is the surface area of a cone with a slant of 9 cm and a height of 7 cm?

Aug 13, 2016

$= 260.47 c {m}^{2}$

#### Explanation:

$r = \sqrt{{l}^{2} - {h}^{2}}$ where $l = s l a n t = 9 \mathmr{and} h = h e i g h t = 7 \mathmr{and} r = r a \mathrm{di} u s$ of a Cone
or
$r = \sqrt{{9}^{2} - {7}^{2}}$
or
$r = \sqrt{81 - 49}$
or
$r = \sqrt{32}$
or
$r = 5.66$
Surface Area of a Cone $= \pi r \left(r + l\right) = \pi \times 5.66 \times \left(5.66 + 9\right) = 260.47 c {m}^{2}$