[Fig. 45].—The tetrahedron, bounded by four equilateral triangles.
[Fig. 46].—The hexahedron, or cube, bounded by six squares.
[Fig. 47].—The octahedron, bounded by eight equilateral triangles.
[Fig. 48].—The dodecahedron, bounded by twelve pentagons.
[Fig. 49].—The icosahedron, bounded by twenty equilateral triangles.
PRISM.—A solid whose bases or ends are very similar plane figures, and whose sides are parallelograms; prisms are called triangular, square, etc., according as the bases are triangles, squares, etc.
PRODUCE.—To continue or extend.
PROFILE.—An outline or contour.
PROJECTION.—The view of an object obtained upon a plane by projecting lines perpendicular to the plane.
QUADRANT.—The fourth part; a quarter; the quarter of a circle.