Self-intersecting polygons, crossed polygons, or self-crossing polygons are

polygon In geometry, a polygon () is a plane figure made up of line segments connected to form a closed polygonal chain. The segments of a closed polygonal chain are called its '' edges'' or ''sides''. The points where two edges meet are the polygon ...

s some of whose edges cross each other. They contrast with

simple polygon In geometry, a simple polygon is a polygon that does not Intersection (Euclidean geometry), intersect itself and has no holes. That is, it is a Piecewise linear curve, piecewise-linear Jordan curve consisting of finitely many line segments. The ...

s, whose edges never cross. Some types of self-intersecting polygons are: *the crossed quadrilateral, with four edges **the antiparallelogram, a crossed quadrilateral with alternate edges of equal length ***the crossed rectangle, an antiparallelogram whose edges are two opposite sides and the two diagonals of a

rectangle In Euclidean geometry, Euclidean plane geometry, a rectangle is a Rectilinear polygon, rectilinear convex polygon or a quadrilateral with four right angles. It can also be defined as: an equiangular quadrilateral, since equiangular means that a ...

, hence having two edges parallel * Star polygons ** pentagram, with five edges ** hexagram, with six edges ** heptagram, with seven edges ** octagram, with eight edges ** enneagram or nonagram, with nine edges ** decagram, with ten edges ** hendecagram, with eleven edges **

dodecagram In geometry, a dodecagram (γραμμή
Henry George Liddell, Robe ...

, with twelve edges ** icositetragram, with twenty four edges ** 257-gram, with two hundred and fifty seven edges

See also