The radius is the distance from the center of a circle to the circumference. This is half of the diameter which is the longest distance across a circle.
The circumference is the perimeter of the circle. It is calculated with 2pi*radius
The area is calculated with pi*radius^2
The answers are as followed:
- Radius: 8/2 = 4 inches
- Circumference: 2*3.14*4 = 25.12 or 8pi inches
- Area: 3.14*4^2 = 50.24 or 16pi inches