- a technique for establishing the distance between any two points, or the relative position of two or more points, by using such points as vertices of a triangle or series of triangles, such that each triangle has a side of known or measurable length (base, or base line ) that permits the size of the angles of the triangle and the length of its other two sides to be established by observations taken either upon or from the two ends of the base line.
- the triangles thus formed and measured.
- a method of surveying in which an area is divided into triangles, one side (the base line) and all angles of which are measured and the lengths of the other lines calculated trigonometrically
- the network of triangles so formed
- the fixing of an unknown point, as in navigation, by making it one vertex of a triangle, the other two being known
- a key manoeuvre in the endgame in which the king moves thrice in a triangular path to leave the opposing king with the move and at a disadvantage
