00:02
Okay, so the problem we have here is that a sphere is contained in a cube and it is tangent to all six spaces of the cube.
00:10
We need to find the surface area of the cube as a function of the radius of the sphere.
00:15
Okay, so i have my cube and my sphere here, and let's just call the side length of the cube x.
00:24
We know that each of those side lengths are the same x because it's a cube.
00:30
Now, because the sphere is tangent to all six faces, that means the sphere touches this left face, and it stretches and touches this right face.
00:44
It's touching all the middle of six faces of the cube together.
00:51
Okay.
00:52
So we already know that the one face of the sphere extends from one side of the cube.
01:01
All the way to the other side of the cube.
01:03
And we know that this length is just the diameter d of this sphere.
01:09
Ok, so we could say that x is just equal to d...