# Thread: what is the total surface area of the cone

1. ## what is the total surface area of the cone

here is the link to the cone question can you answer it and show how.

IMG_1368.jpg picture by BradCelt - Photobucket

Mr F edit: This is a duplicate question also asked here: http://www.mathhelpforum.com/math-he...area-cone.html

2. Originally Posted by gilzean
here is the link to the cone question can you answer it and show how.

IMG_1368.jpg picture by BradCelt - Photobucket

Hi gilzean,

This is just a "plug and chug" formula problem. The formula for the Surface Area of a cone is:

$\displaystyle S.A.=\pi rs + \pi r^2$, where

s = slant height of cone

If you don't need the area of the base of the cone, then don't add the $\displaystyle \pi r^2$

3. i dont understand , radius = 10cm slant height= 15cm

total surface area = ????? ??? please???

4. Originally Posted by gilzean
i dont understand , radius = 10cm slant height= 15cm

total surface area = ????? ??? please???
Substitute and solve.

$\displaystyle S.A.=\pi rs + \pi r^2$, where

s = slant height of cone

$\displaystyle S.A=\pi (10)(15)+\pi(10^2)$

$\displaystyle S.A.=150 \pi + 100 \pi$

$\displaystyle S.A.=250 \pi$

$\displaystyle S.A. \approx 785.4 cm^2$

Then leave it as $\displaystyle S.A.=250 \pi$