Smooth

A = pi * radius2

It is the same as finding the area of a circle which is: pi*radius2

The area of the sector is a fraction of the area of the whole disk. So, we need to find the area of the whole disk and then multiply by the ratio of the sector size to the disk. The ratio is 2/3 pi out of a disk that is 2 pi all around (like any circle). Twos cancel, "pi"s cancel, so the sector is 1/3 of the disk. The disk's area is pi times (the radius squared). Pi times four. Well, to avoid using irrational numbers, the disk's area is 4 pi. The sector is 1/3 of 4 pi square feet, which is 4/3 pi square feet.

optic disk