And on the left-hand side, 36 divided by 2 is 18. The pi's cancel out. We get our radius as being equal to 18 for this larger circle. This larger circle has a radius of 18. So if we want to know its area, its area is going to be pi r squared, which is equal to pi times 18 squared. Now let's figure out what 18 squared is. 18 times 18.