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:

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

s = slant height of cone

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

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.

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

s = slant height of cone

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

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

$S.A.=250 \pi$

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

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