Trigonometry

a. [Fr. trigonométrique.]

n. [Fr. trigonométrie, It. & Sp. trigonometria, from Gr. τρίγωνον, a triangle, and μέτρον, measure, μετρεῖν, to measure.] That branch of mathematics which treats of the relations of the sides and angles of triangles, with the methods of deducing from certain parts given other parts required, and also of the general relations which exist between the trigonometrical functions of arcs or angles.

Analytical trigonometry, the branch of trigonometry which treats of the relations and properties of the trigonometrical functions. — Plane trigonometry and spherical trigonometry, the branches of trigonometry in which its principles are applied to plane triangles and spherical triangles respectively.