
The 2Cusped Epicycloid is called a nephroid. Since , , and the equation for
in terms of the parameter is given by Epicycloid equation
(1) 
(2) 
(3) 
(4) 
(5)  
(6) 
(7) 
See also Astroid, Deltoid, Freeth's Nephroid
References
Lawrence, J. D. A Catalog of Special Plane Curves. New York: Dover, pp. 169173, 1972.
Lee, X. ``Nephroid.'' http://www.best.com/~xah/SpecialPlaneCurves_dir/Nephroid_dir/nephroid.html.
Lockwood, E. H. ``The Nephroid.'' Ch. 7 in A Book of Curves. Cambridge, England: Cambridge University Press, pp. 6271, 1967.
MacTutor History of Mathematics Archive. ``Nephroid.'' http://wwwgroups.dcs.stand.ac.uk/~history/Curves/Nephroid.html.
Yates, R. C. ``Nephroid.'' A Handbook on Curves and Their Properties. Ann Arbor, MI: J. W. Edwards, pp. 152154, 1952.
© 19969 Eric W. Weisstein