trisection

[Lat. tri =three, and sectio=a cutting, a section.] The division or cutting of any. thing into three parts; spec if., in geometry, the division of an angle into three equal parts. The trisection of an angle is a problem of great celebrity among the ancient mathematicians. It belongs to the same cla of problems as the duplication of the cube, and the insertion of two geometrical means between two given lines. Like them, it has hitherto been found beyond the range of elementary geometry; but it may be effected by means of the conic sections, and some other curves, as the conchoid, quadratrix, . tri-sē ́-pal-oŭs, a . [Pref. tri- , and Eng.sepalous .] Bot . ( of a calyx ): Consisting of three sepals. tri-sër-I-al, tri-sër-I-ate, a. [Pref. tri- , and Eng. serial , seriate (q. v.).] Bot.: Arranged in three rows, which are not nece arily opposite to each other; trifarious.