Trigonometrical curve, a curve one of whose coördinates is a trigonometric function of the other. Trigonometrical function. See under Function.Trigonometrical lines, lines which are employed in solving the different cases of plane and spherical trigonometry, as sines, tangents, secants, and the like. These lines, or the lengths of them, are trigonometrical functions of the arcs and angles to which they belong.Trigonometrical survey. See under Survey.

Trigonometry
(Trig`o*nom"e*try) n.; pl. -tries [Gr. a triangle + -metry: cf. F. trigonométrie. See Trigon.]

1. That branch of mathematics which treats of the relations of the sides and angles of triangles, which the methods of deducing from certain given parts other required parts, and also of the general relations which exist between the trigonometrical functions of arcs or angles.

2. A treatise in this science.

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

Trigonous
(Trig"o*nous) a. [L. trigonus, Gr. . See Trigon.] Same as Trigonal.

Trigram
(Tri"gram) n. [Pref. tri- + - gram.] Same as Trigraph.

Trigrammatic
(Tri`gram*mat"ic) a. [Gr. + a letter.] Containing three letters or characters, or three sets of letters or characters.

Trigness
(Trig"ness) n. [See Trig trim, neat.] The quality or state of being trig; smartness; neatness.

Their spars had no man-of-war trigness.
Kane.

Trigon
(Tri"gon) n. [L. trigonum, Gr. (see Tri-) + a corner, angle: cf. F. trigone.]

1. A figure having three angles; a triangle.

2. (Astrol.) (a) A division consisting of three signs. (b) Trine, an aspect of two planets distant 120 degrees from each other. Hutton.

3. (Gr. & Rom. Antiq.) (a) A kind of triangular lyre or harp. (b) A kind of game at ball played by three persons standing at the angular points of a triangle.

Trigonal
(Trig"o*nal) a. Having three angles, or corners; triangular; as, a trigonal stem, one having tree prominent longitudinal angles.

Trigone
(||Tri`gone") n. [F., literally, a trigon.] (Anat.) A smooth triangular area on the inner surface of the bladder, limited by the apertures of the ureters and urethra.

Trigonia
(||Tri*go"ni*a) n. [NL. See Trigon. So called in allusion to the triangular shape of some species.] (Zoöl.) A genus of pearly bivalve shells, numerous extinct species of which are characteristic of the Mesozoic rocks. A few living species exist on the coast of Australia.

Trigonocerous
(Trig`o*noc"er*ous) a. [Gr. triangle + horn.] (Zoöl.) Having horns with three angles, like those of some species of goats.

Trigonometric
(Trig`o*no*met"ric Trig`o*no*met"ric*al) [Cf. F. trigonométrique.] Of or pertaining to trigonometry; performed by the rules of trigonometry.