It is an arc
An arc is a portion of the circumference
An arc is a portion of the circumference of a circle.
circumference = 2*pi*radius or pi*diameter
An arc
The circumference of a circle = pi*diametre = 2pi*radius
The equator.
Then they are similar.
Pi times the diameter of a circle gives its circumference.
The ratio of the circumference of a circle to its diameter is Pi. (3.14159)
A part of the circumference is called an arc. If the circumference is split into two unequal arcs then the larger portion is referred to as the major arc and the lesser portion as the minor arc.
Circumference is a special name for a circles perimeter. I think the answer you are looking for is radious.
Any circle's circumference can be calculated with the formula 2(pi)*radius