# Lune (geometry)

(Redirected from Lune (mathematics))
 In plane geometry, the crescent shape formed by two intersecting circles is called a lune. In each diagram, two lunes are present, and one is shaded in grey.

In plane geometry, a lune is the concave-convex area bounded by two circular arcs, while a convex-convex area is termed a lens. [1] The word lune derives from luna, the Latin word for "moon".

Formally, a lune is the relative complement of one disk in another (where they intersect but neither is a subset of the other). Alternatively, if ${\displaystyle A}$ and ${\displaystyle B}$ are disks, then ${\displaystyle A-A\cap B}$ is a lune.

## Example

In the 5th century BC, Hippocrates of Chios showed that certain lunes could be exactly squared by straightedge and compass.