See also: Triangle (homonymy)

In Geometry, a Triangle is defined on a Surface like a figure closed in three sides, these three sides being arcs of Géodésique S of this surface. This surface can be inter alia spherical, hyperbolic or planes, and the corresponding triangles are known as spherical , hyperbolic or plans.

Properties

Contrary to the Triangle defined in Euclidean Geometry, the sum of the angles of a triangle can be different from 180°. For example, the sum of the angles of a spherical triangle is higher than 180°

There thus exist right-angled triangles, birectangles or trirectangular which have one respectively, two and three right angles.

See Too

• spherical Trigonometry