Definition:Circle/Circumference

Definition

The circumference of a circle is the line that forms its boundary.

Concave Circumference

The convex circumference of a circle $C$ is the circumference $C$ from a point outside $C$.

Concave Circumference

The concave circumference of a circle $C$ is the circumference $C$ from a point inside $C$.

Also defined as

The term circumference is also used to refer to the length of the boundary.

Technically, the correct term for the length of the circumference is perimeter.

Also see

• Results about circumferences can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): circumference: 1.
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): circumference: 1.
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): circumference