What's the deal?
circle = a closed shape with all of the points the same distance from the center
radius = the distance from the center to the outside of the circle
diameter = the distance across the circle, going through the center; 2 radii
circumference = a special work for the perimeter of the circle
What is pi??
Pi is a special number. Pi is found in every single circle in the world. It's the ratio of the circumference to the diameter.
In other words, if you measure the circumference of ANY circle and divide it by the diameter of that circle, you'll always get pi!
We use 3.14 to represent pi because it's easier to work with.
There are two ways to find the circumference:
pi x diameter OR (3.14 x diameter)
pi x radius x 2 (3.14 x radius x 2)