The original point that we started with, that’s called the or the origin of the circle.
Next, we have the that we used to draw all of the equidistant points that form the circle. That distance is called the .
The radius is important because it’s the distance from the center of a circle to other point on the perimeter of that circle.
The is the distance across a circle. The diameter is really just the same as two radius lines drawn in exactly opposite directions.
So for any circle, the diameter is always exactly twice as long as the radius.