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Evolvent

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An evolvent is a region in the plane that is isometric to a given region on a developable surface. Example: The evolvent of the side surface of a cone cut along a generator is a planar sector. The approximate construction of an evolvent can be achieved graphically by means of descriptive geometry.

The evolvent of a polyhedral surface is a set of polygons (the faces of the evolvent) with a rule for glueing their sides that defines a polyhedral metric isometric to the internal geometry of the polyhedral surface. The faces of the evolvent need not coincide with the real faces of the surface: when laid on the surface they may be folded.


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References

[a1] W. Blaschke, K. Leichtweiss, "Elementare Differentialgeometrie" , Springer (1973)
How to Cite This Entry:
Evolvent. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Evolvent&oldid=18491
This article was adapted from an original article by V.A. Zalgaller (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article