How does the equation of a circle work? What do the individual parts represent?

A student will often see the equation of a circle in the form (x-a)²+(y-b)²=r². In this instance, a and b simply represent numbers. They are not variables. In fact, a represents the x co-ordinate of the centre of the circle and b represents its y co-ordinate. This is an easy way to find out the centre point of your circle. The value on the right side of the equation, represents the radius of the circle squared. This will give you the length of the distance between the edge of the circle and its centre when square rooted. It is important when answering questions like this that you remember that the value is squared and must be square rooted in order to get the radius. X and Y in this equation are simply variables as in any other function such as y=mx+c.