Sfärisk

Sfærisk is an adjective used in Danish and Norwegian to denote something related to a sphere or spherical in form. The term is used in mathematics, physics, and everyday language to describe objects, surfaces, or properties that pertain to a sphere.

In geometry, sfærisk relates to spherical geometry—the study of figures on the surface of a sphere rather than in the plane. A key feature is positive constant curvature; straight lines are replaced by great circles, which are the shortest routes on the sphere.

Common concepts include sfærisk coordinates, a three-parameter system used to specify positions on a sphere, and sfærisk trigonometry, which deals with angles and sides on the spherical surface. Spherical surfaces appear in many fields, from map projections to optics.

Applications include navigation, astronomy, geodesy, computer graphics, and acoustics. The Earth is often modeled as a sphere, and sfærisk methods underpin satellite trajectories, weather models, and the representation of signals on a sphere using spherical harmonics.

Etymology: sfærisk derives from Latin sphaera and Greek sphaira, entering Danish and Norwegian through historical scientific terminology. It is closely related to the English term spherical, sharing the same root.

See also: sphere; spherical geometry; spherical coordinates; great circle; geodesy.