circumference of a circle

Circumference

The perimeter of a circle.

Pi ($ext{π}$)

A mathematical constant representing the ratio of circumference to diameter, known for its infinite nature.

Formula for Circumference (from radius)

$C = 2 ext{π} r$.

Formula for Circumference (from diameter)

$C = ext{π} d$.

Relationship between diameter and radius

The diameter ($d$) is equal to twice the radius ($d = 2r$).

Common mistake in calculating circumference

Forgetting to double the radius when calculating diameter.

Constant ratio of circumference to diameter

The ratio is always $ext{π}$.

Practical applications of circumference

Used in everyday activities such as baking and mechanics.