Convex polygon
From Wikipedia, the free encyclopedia
In geometry, a convex polygon is a simple polygon whose interior is a convex set. The following properties of a simple polygon are all equivalent to convexity:
- Every internal angle is at most 180 degrees.
- Every line segment between two vertices of the polygon does not go exterior to the polygon (i.e., it remains inside or on the boundary of the polygon).
A simple polygon is strictly convex if every internal angle is strictly less than 180 degrees. Equivalently, a polygon is strictly convex if every line segment between two vertices of the polygon is strictly interior to the polygon except at its endpoints.
Every triangle is strictly convex.
[edit] Concave polygon
If a simple polygon is not convex, it is called concave. At least one internal angle of a concave polygon is larger than 180 degrees.
A concave polygon is often called re-entrant polygon (but in some cases the latter term has a different meaning).
[edit] External links
- Definition and properties of convex polygons With interactive animation
- Definition and properties of concave polygons With interactive animation
