Bifoliate

$\begin{figure}\begin{center}\BoxedEPSF{Bifoliate.epsf scaled 500}\end{center}\end{figure}$

The Plane Curve given by the Cartesian equation

$\begin{displaymath} x^4+y^4=2axy^2. \end{displaymath}$

References

Cundy, H. and Rollett, A. Mathematical Models, 3rd ed. Stradbroke, England: Tarquin Pub., p. 72, 1989.