00:01
So say we're trying to find the area for a cylinder.
00:05
A cylinder just like this.
00:08
What we know about the cylinder is that it has some radius r, and the height is three units longer than the radius.
00:20
And the last thing we know about it is that the area of the base is 25 pi.
00:32
So how do we figure this out? well, hopefully we're thinking that we first need to figure out r is and we can do that using this piece of the right we know that the area of a circle is equal to pi r squared and in this case that area equals 25 pi so we can use this to solve for r right if we divide both sides of our equation here by pi we're left with r squared equals 25 and then if we take this square root of both sides.
01:08
We get that r is 5.
01:12
And we know it's positive 5 because we're dealing with a geometric object, right, that has a real length.
01:19
So our radius is 5.
01:20
And that means we know immediately that our height equals 8, right? our radius, our height was radius plus 3, so we know it's 8...