A Folium with . The bifolium is the Pedal Curve of the Deltoid, where the Pedal Point is the
Midpoint of one of the three curved sides. The Cartesian equation is

and the Polar equation is

**References**

Lawrence, J. D. *A Catalog of Special Plane Curves.* New York: Dover, pp. 152-153, 1972.

MacTutor History of Mathematics Archive. ``Double Folium.'' http://www-groups.dcs.st-and.ac.uk/~history/Curves/Double.html.

© 1996-9

1999-05-26