trigonometry
branch of mathematics that studies triangles and the relationships between their sides and the angles between these sides
rational trigonometry
reformulation of planar distance and angle measurements in terms of polynomial functions of Cartesian coordinates
generalized trigonometry
study of triangles in other spaces than the Euclidean plane
spherical trigonometry
branch of spherical geometry that deals with the relationships between trigonometric functions of the sides and angles of the spherical polygons.