The diameter of the circle is the double of it's radius.
diameter is a line from a point of the circle to another point passing through the center of the circle
yes it is it the distance from side to side passing through the center of the circle
Diameter is a line that touches any two points in a circle, which must pass through the center of the circle. If you half the diameter, it will be the radius, r of the circle, so it is like saying two times the "r" value, like this: D=2r. It helps you to solve circumference of the circle, the equation being pi*d