reunapituus

Reunapituus is a term used in geometry to denote the length of an edge in a geometric object. In Finnish, reuna means boundary or edge and pituus means length. The term is commonly applied to polygons, polyhedra, and mesh representations, where each edge has a measurable length.

In a polygon, each edge e_i has a length l_i, defined as the distance between its endpoints. The collection of edge lengths {l_i} describes the shape at the granularity of edges, while the perimeter P of the polygon is the sum of all edge lengths: P = sum l_i.

In three-dimensional objects, such as polyhedra or polygonal meshes, edges connect pairs of vertices and possess a length computed by the Euclidean distance in 3D space. When a figure is regular (all edges equal), a common edge length is sometimes referred to as the reunapituus of the object.

Edge length is computed by standard distance formulas: in 2D, l = sqrt((x2−x1)^2 + (y2−y1)^2); in 3D, l = sqrt((x2−x1)^2 + (y2−y1)^2 + (z2−z1)^2).

Applications include computer graphics, mesh generation, finite element analysis, architectural modeling, and geographic information systems, where knowing edge lengths helps in measuring, meshing quality, and geometric optimization.

See also: perimeter, edge, distance, Euclidean metric. The term reflects Finnish terminology in geometry and is commonly found in textbooks and technical literature.