Geometric Model by A. Harry Wheeler, Supplementary Trihedral Angles

Geometric Model by A. Harry Wheeler, Supplementary Trihedral Angles

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Three planes that meet at the center of a sphere form what is called a trihedral (three-sided) angle. Each plane intersects the sphere in a great circle. Segments of these three circles form a spherical triangle on the sphere. In this cut and folded tan paper model, Wheeler labels the vertices of this triangle ABC. Consider a point (not named by Wheeler – call it X) inside the bounds of the trihedral angle and drop perpendiculars to the three sides of the trihedral angle through it. Wheeler calls the points of intersection D, E, and F. The trihedral angle centered at X is the supplement of the original trihedral angle.
D. A. Low, Practical Geometry and Graphics, New York: Longmans, Green and Co., 1912, pp. 233-235.
Currently not on view
Object Name
Geometric Model
date made
1927 05 29
Wheeler, Albert Harry
place made
United States: Massachusetts, Worcester
Physical Description
paper (overall material)
tan (overall color)
cut and folded (overall production method/technique)
average spatial: 7 cm x 7.3 cm x 6 cm; 2 3/4 in x 2 7/8 in x 2 3/8 in
ID Number
accession number
catalog number
Credit Line
Gift of Helen M. Wheeler
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Spherical Trigonometry
Data Source
National Museum of American History
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