a. [f. TRIGONOMETRY or mod.L. trigonometria + -IC + -AL; after geometrical, etc.] Of, pertaining to, or performed by trigonometry.
Trigonometrical functions, those functions of an angle, or of an abstract quantity, used in trigonometry, viz. the sine, tangent, secant, etc.: see TRIGONOMETRY. Trigonometrical survey, a survey of a country or region performed by triangulation and trigonometrical calculation.
1666. [implied in TRIGONOMETRICALLY].
1690. Leybourn, Curs. Math., 552. To find the Altitude … by Trigonometrical Calculation.
1706. W. Jones, Syn. Palmar. Matheseos, 278. Any three … being given, the other three may be found by Trigonometrical Calculation.
1758. Murdoch, in Phil. Trans., L. 543. A table of the trigonometrical analogies.
1801. Cart. W. Madge (title), Account of the Operations carried on for accomplishing a Trigonometrical Survey of England and Wales, 1797.
1807. Hutton, Course Math. (1811), II. 3. A Trigonometrical Canon is a table showing the length of the sine, tangent, and secant, to every degree and minute of the quadrant, with respect to the radius, which is expressed by unity or 1.
1860. Tyndall, Glac., I. xi. 69. A pyramid of stones used as a trigonometrical station by Professor Forbes.
