Geom. [f. after HOMOGRAPHY: see TRI-.] A group of three sets of points or lines having a relation analogous to that of homography between two (see HOMOGRAPHY 1); that branch of geometry which deals with such relations. Hence Trigraphic a., pertaining to trigraphy.
1895. J. W. Russell in Proc. Lond. Math. Soc., XXVI. 446 (title), Applications of Trigraphy…. Trigraphic ranges…. A trigraphy projects into a homographic trigraphy. Ibid., 448. Given the trigraphic relation, to construct the vague points. Ibid., 450. Trigraphic Pencils. Ibid., 452. Trigraphic Properties of a Quadric Surface.
