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Surface Area of a Cube 5082 Views
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Description:
Good thing surface areas are as easy as they seem on the surface.
Transcript
- 00:06
Surface of a Cube, a la Shmoop. Harold the hobo would like to cover his new
- 00:12
box while he sleeps at night...
- 00:14
...so no one sees it and tries to steal it.
- 00:18
Harold's not the smartest knife in the drawer. Man, he sure wishes he had a drawer.
- 00:23
Assuming Harold knows the volume of the cube is 1,728 milliliters...
Full Transcript
- 00:27
...how much material will he need to make a perfect-fitting box cozy?
- 00:32
We can use the cube's volume to help Harold figure out its surface area.
- 00:37
Here are our choices:
- 00:39
First, let's break down that box. We can start by working backwards.
- 00:46
We know that the volume of our cube is 1,728. So now we need to work backwards.
- 00:51
Volume is length times width times height.
- 00:54
Lucky for us, all are the same length in a cube.
- 00:57
To find volume, we can raise length, width or height to the third power... or cube it.
- 01:04
So we simply need to take the cube root of the volume.
- 01:07
The cube root of 1,728 is 12.
- 01:18
There's our length, width and height.
- 01:22
Now let's find the surface area of one side.
- 01:25
Multiply the box's width by its height.
- 01:27
So that is 12 times 12, which gives us 144... How many sides are there again, Harold?
- 01:34
Yep... six of 'em.
- 01:37
So 144 times 6 equals... 864.
- 01:42
Choice E, you're the winner!
- 01:44
Now Harold has enough material to hide his home...
- 01:48
...and doesn't have to worry about some box-thief filching it in the night.
- 01:59
Sleep tight, Harold. Don't let the literal bed bugs bite.
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