Beman, Wooster Woodruff, 1850-1922, Smith, David Eugene, 1860-1944 · Boston, Ginn & company · leaf 295
trihedralangles, and prop. XXVII repeatedly applied. Note. Prop. XXVII and corollaries suppose that each face-angle isless than a straight angle. This is in accordance with the note underthe definition of a polyhedral angle. 376. Definition. A polyhedral angle is said to be convexwhen any polygon… … Given any convex polyhedral angle, V-ABC To prove that Z A VB + Z B VC + Z C VI) + < perigon. Proof. 1. Let the faces of the angle be cut by a plane. Thiswill form a convex polygon of n sides (n = 5 in thefigure), abc Def. convex polyh. Z Prop. XXV1II.J POLYHEDRAL ANGLES. 279 Let Sv = sum of…
Geometry
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