¶ Octahedron (2)
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Index Entry
Octahedron
“There is a center of gravity of the octahedron and it has eight equilateral triangular faces and there is a little pyramid, or irregular tetrahedron which can be formed on one of the faces of the octahedron whose interior apex is at the center of gravity of the octahedron. . . Because there are eight such faces and it is at the center of volume, there are eight of thes that make up one octahedron so this is a one-eighth octahedron. If the volume of an octahedron is four, the one-eighth of an octahedron has the volume of one-half of one tetrahedron.”
"Each of the one-eighth octahedra &as interiorly 90-degree angles because they are the XYZ coordinates and when the XYZ coordinates cross, it is 90 degrees. They have a central angle of 90 degrees and the external angles are 60 degrees each. . . Cite Oregon Lecture #6, p. 215. 10 Jul’62
