How to Find Surface Area of a 3D Shape

How to Find Surface Area of 3D Shapes

Hi, and welcome to this video lesson on surface area of three dimensional objects.

3D objects can sometimes intimidate us in math, especially when given to us in a word problem, but don’t fear, they break down into steps very nicely.

Lets try one together. Right, so what do we know? Well, we know that we need the surface area of a 3D object is the sum of the surface area of its six sides. In our problem, we know we have a height of 4 a width of 20 and a length of 32.

We have a total of six sides, so lets figure out what those areas will be.

Ends: height times width times two

Short sides: height times length times two

Big sides: length times width times two

Or, more simply

h*w*2 =

h*l*2 =

l*w*2 =

So let’s figure out our actual area now.

h*w*2 = 4*20*2 = 160

h*l*2 = 4*32*2 = 256

l*w*2 = 32*20*2 = 1280

We add the sums of all those sides together to get our total surface area.

160 + 256 + 1280 = 1696 = Total SA

I hope that helps. Thanks for watching this video lesson, and until next time, happy studying.



by Mometrix Test Preparation | Last Updated: February 19, 2019