Viisikulmainen

Viisikulmainen is a Finnish adjective meaning five-angled or five-sided. It is used to describe shapes that have five corners, most commonly polygons with five sides. In geometry, a five-sided polygon is referred to as viisikulmainen, with the most common example being the pentagon.

In a five-sided polygon, the sum of interior angles is (5−2)×180 = 540 degrees. A regular viisikulmainen polygon has five equal interior angles of 108 degrees and five equal sides. The exterior angles of a regular viisikulmainen polygon sum to 360 degrees, with each exterior angle measuring 72 degrees. The term is also applicable to three-dimensional figures that feature pentagonal faces, such as pentagonal prisms or pentagonal pyramids, described in Finnish as viisikulmainen prisma or viisikulmainen pyramidi.

Etymology and usage: the word combines viisi (five) and kulma (angle) with the comparative suffix -mainen, forming a generic descriptor for objects or figures that possess five angles or corners. Beyond pure geometry, viisikulmainen can appear in design, architecture, and crystallography to characterize five-angled forms or motifs.

See also: pentagon; pentagonal tiling; pentagonal prism.