That is, in triangles "ABC" and "DEF" with sides "a", "b", "c", and "d", "e", "f" respectively (with "a" opposite "A" etc.), if "a" = "d" and "b" = "e" and angle "C" > angle "F", then  The converse also holds: if "c" > "f", then "C" > "F". The angles in any two triangles "ABC" and "DEF" are related in terms of the cotangent function according to  In a triangle on the surface of a sphere, as well as in elliptic geometry,  This inequality is reversed for hyperbolic triangles.