Text-book of Euclid's elements for the use of schools : books I - VI and XI (1900)
Hall, H. S. (Henry Sinclair), 1848-1934, Stevens, F. H. (Frederick Haller), 1853-1933 · MacMillan : London · leaf 438
DEFINITIONS. 417 (v) A regular icosahedron isa solid figure bounded by twenty plane faces, which are equal andequilateral triangles. … Solids of Revolution. 22a. A sphere is a solid figure described by the revo-lution of a semicircle about its diameter, which remainsfixed. The axis of the sphere is the fixed straight line about which thesemicircle revolves. The centre of the sphere is the same as the centre of the semi-circle. A…
Geometry · Mathematics
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