[Review - A circle is a set of points on a plane that are a certain distance from the same point.]
Fact 1: Circles have a centerpoint. This is the point that is listed above as the same point that all of the points on the circle are the same distance from.
Look at the picture above. In this picture is a cross-section of a grapefruit that I cut in half. The outside skin of the grapefruit is what we are calling the "circle". Inside the circle there are three points represented by three seeds. Two of the seeds are just points that happen to be inside the circle. These are points that aren't on the circle and aren't in the exact center of the circle either.
Only one seed can represent the centerpoint of the circle, because there is only one center of each circle. The seed that is circled in red is the centerpoint of our grapefruit circle. On a real circle, there will be a letter beside this centerpoint. The letter by the centerpoint will be the name of the circle.
To learn more about the center of a circle, click here. This website gives you an interactive experience
with the properties of a circle and is pretty fun, too!
Next!