Cosine of the angle is called the relation of a leg, adjacent to this corner, to a hypotenuse. This size, as well as other trigonometrical ratios, is used for the decision not only rectangular triangles, but also many other tasks.
Feudal ladder – the system of the hierarchical relations between feudal lords. Consists in personal dependence of some feudal lords on others. The principle of a feudal ladder had wide circulation in Western Europe.
