Spherical trigonometry is a branch of spherical geometry which deals with polygons (especially triangles) on the sphere and the relationships between the sides and the angles. This is of great importance for calculations in astronomy and earth-surface, orbital and space navigation.
Read more about Spherical Trigonometry: History, Lines and Angles On A Sphere, Congruent Triangles On A Sphere, Identities, Solution of Triangles