A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 222
on altitude. S09. If the generatrix be considered as an indefinite straightline passing through a fixed point, the portions of the line on oppo-site sides of the point will each describe a conical surface. Thesetwo surfaces, which in general discussions are considered but one, arecalled Nappes, The… … Fio. 304. cessive positions of the point A, as it passes around the curve, while the point Sremains fixed. (&) represents a Cone of Bewlution, or a right cone with a cir-cular base. It may be considered as generated in the general way, or by theright angled triangle SOA revolving about SO as an…
Geometry · Trigonometry
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