Conchoid
A curve whose name means ``shell form.'' Let 
be a curve and 
a fixed point. Let 
and 
be points on a linefrom to meeting it at 
, where 
, with 
a given constant. For example, if is aCircle and is on , then the conchoid is a Limaçon, while in the special case that is the Diameter of , then the conchoid is a Cardioid. The equation for a parametrically representedcurve 
with 
is
See also Concho-Spiral, Conchoid of de Sluze, Conchoid of Nicomedes, Conical Spiral,Dürer's Conchoid
References
Lawrence, J. D. A Catalog of Special Plane Curves. New York: Dover, pp. 49-51, 1972. Lee, X. ``Conchoid.''http://www.best.com/~xah/SpecialPlaneCurves_dir/Conchoid_dir/conchoid.html. Lockwood, E. H. ``Conchoids.'' Ch. 14 in A Book of Curves. Cambridge, England: Cambridge University Press, pp. 126-129, 1967. Yates, R. C. ``Conchoid.'' A Handbook on Curves and Their Properties. Ann Arbor, MI: J. W. Edwards, pp. 31-33, 1952.
- Penrose Tribar
- Pentabolo
- Pentacle
- Pentacontagon
- Pentad
- Pentadecagon
- Pentaflake
- Pentagon
- Pentagonal Antiprism
- Pentagonal Cupola
- Pentagonal Deltahedron
- Pentagonal Dipyramid
- Pentagonal Gyrobicupola
- Pentagonal Gyrocupolarotunda
- Pentagonal Hexecontahedron
- Pentagonal Icositetrahedron
- Pentagonal Number
- Pentagonal Orthobicupola
- Pentagonal Orthobirotunda
- Pentagonal Orthocupolarontunda
- Pentagonal Prism
- Pentagonal Pyramid
- Pentagonal Pyramidal Number
- Pentagonal Rotunda
- Pentagonal Tiling