| 释义 |
pyramidoid Geom. rare.|pɪˈræmɪdɔɪd|
[ad. mod.L. pȳramidoīdes (sc. schēma): see pyramid and -oid.]
A solid figure in form approaching a pyramid, but of which the edges that meet or intersect at the vertex are curves, instead of straight lines as in a pyramid; as the parabolic pyramidoid, in which the vertical sections through the edges are parabolas instead of triangles.
[1655J. Wallis De Sectionibus Conicis Prop. ix, De Conoide et Pyramidoide Parabolico. Ibid. xiv, De Elliptico Pyramidoide et Conoide. 1656― Arithmetica Infinitorum Prop. iv, Item, Pyramidoides vel Conoides Parabolicum..ad Prisma vel Cylindrum (super æquali base æquealtum) est ut 1 ad 2.] 1704J. Harris Lex. Techn. I, Parabolick Pyramidoid..so named by Dr. Wallis from its Genesis, or Formation. 1795Hutton Math. Dict. s.v. Parabola.
¶ Erroneously identified with a parabolic spindle.
1710J. Harris Lex. Techn. (ed. 2) II. s.v.; thence 1727in Bailey vol. II, and 1730folio; 1839 Encycl. Brit. XVIII. 746/2; and some recent Dicts.
So pyramiˈdoidal a., (a) Of or pertaining to a pyramidoid. (b) Of the general figure of a pyramid upon a base of any shape.
1807T. Young Nat. Philos. II. 20 All pyramidoidal solids are equal to one third of the circumscribing prismatic or cylindroidal solids of the same height. |