00:01
Okay, so here we're told that we have a cylinder.
00:03
We're given the formula to find the surface area of a cylinder, and we're told that this particular cylinder has a height of four, and its total surface area is calculated as 200 square feet.
00:14
All right.
00:15
So first part of problem says express the radius as a function in terms of v.
00:20
Well, we know that for a cylinder, the volume is going to be equal pi r squared times the height.
00:28
But in this case, we know the height is four.
00:30
So from now on, wherever we see h, we'll replace it with a 4.
00:33
Okay, so our volume is actually 4 pi r squared.
00:39
Now, we want to solve r.
00:41
So we're going to go ahead and divide both sides by 4 pi, and we get that r squared is equal to v over 4 pi.
00:51
To get r in its own, we take the square root of both sides.
00:55
R is equal to, now we see 4 is actually a perfect square, so we can pull it out on the bottom.
01:01
So r is one half of the square root of v over pi.
01:06
All right...
