- A method of surveying over long distances by establishing a network of triangles. Most sides in the network are computed from a known side that may be calculated, and two measured angles. Lengths are measured periodically as a check.
- The location of an unknown point, such as that of a ship or airplane, by forming a triangle in which two known points serve as the other two vertices, and using geometry to determine the location of said unknown point. Used, for instance, in radio navigation.