Stadium (geometry)

A stadium is a two-dimensional geometric shape constructed of a rectangle with semicircles at a pair of opposite sides.

[6] The shape is based on a stadium, a place used for athletics and horse racing tracks.

However, unlike some other ovals such as the ellipses, it is not an algebraic curve because different parts of its boundary are defined by different equations.

Leonid Bunimovich used this shape to show that it is possible for billiard tracks to exhibit chaotic behavior (positive Lyapunov exponent and exponential divergence of paths) even within a convex billiard table.

[8] A capsule is produced by revolving a stadium around the line of symmetry that bisects the semicircles.