Equations of a Circle: Introduction

Drop of water making concentric circles

As a drop hits the top of the water, ripples begin to grow outward, making circle outside of circle, outside of circle.  These are called concentric circles.  Concentric circles have the same center points, but different length radii.  In this section, we are going to look at equations that define a circle.  Within an equation, you will be able to pick out where the center will be located and you will be able to pick out what the radius length is.