00:01
So we have a closed cylinder, which has a volume equal to pi r squared times the height.
00:08
The surface area is going to be 2 times pi r squared, which is the area of the top and bottom, plus, let's see here, 2 pi r, which is the circumference of the top and bottom, times the height.
00:35
So then the table that we're going to have, the diameter is going to be 2 times the radius, or radius is 1 half the diameter.
00:51
The height is going to be the volume divided by pi r squared, and the surface area, i guess we have to calculate for all of them.
01:13
So then if i know that the height is 14, the volume is 704, then the radius is going to be, let's see here, the radius is the volume divided by h times pi.
01:42
Pi, take the square root of that.
01:45
So this then is going to be 704 divided by the height, which was 14, divided by, let's see here.
02:03
So this is going to be the square root of 704 divided by 14 pi, pi, and that is equal to 4 .00.
02:30
So then the diameter is going to be 8 .00, or just 8.
02:47
And then the surface area, let's see, the formula was 2 times pi r squared plus 2 pi r h.
03:02
So this then is going to be 2 times pi times 4 squared plus 2 pi times 4 times 14.
03:44
And if you want three decimal places, it's going to be 389 centimeters squared.
03:51
Squared.
03:52
Then for the next one, we had a height of 20, volume of 1, 2, 3, 2, 0.
04:00
So that means that your volume is going to be, or your radius is going to be, the square root of 1, 2, 3, 320 divided by, in parentheses, 20 pi, close parentheses...