circumference

The term ‘circumference’ has two meanings:

(1) measurement – the length of the line which forms a circle.

The formula to calculate the circumference of a circle is:

Circumference = π × Diameter
                        = πd

or

Circumference = 2 × π × Radius
                        = 2πr

(2) line – the curved line which forms a circle.

The formulae above can be used to discover the length of this curved line.