Circumference Guide, Meaning , Facts, Information and Description
The circumference is the distance around a closed curve.
Circles
The circumference of a circle can be calculated from its diameter using the formula:
Or, substituting the radius for the diameter:
Where r is the radius and d is the diameter of the circle, and π (the Greek letter pi) is the constant 3.141 592 6...
Ellipses
The circumference of an ellipse is more problematical, the exact solution being an infinite series. A good approximation is Ramanujan's:
where and are the ellipse's semi-major and semi-minor axes, respectively. The two are related by the ellipse's eccentricity as follows:
Which means the circumference can also be written as: