Introductioin of a circle has no meaning - please rephrase the question.
The width, or the length of a circle are its diameter.
It is the length of the base of the semi-circle.
The circumference of a circle is the length of the circle's perimeter.
It'll be the largest chord of the circle.
If you have only the arc length then you cannot find the diameter.
length=n/360*2*pi*radius
the fraction of the circle covered by the arc
if the segment is the whole length of the circle divide it by 2
radius = diameter/2
It depends on what information you do have.
the circumference of a circle is the length around the outer edge. and you find it by using the formula 2 times pi times the radius of the circle
There are a couple of different ways of finding the length of the chord of a circle. Probably the best is what is called the half angle formula.