Bifolium

A bifolium is a quartic plane curve with equation in Cartesian coordinates:

$(x^2+y^2{)}^2=a{x}^{2}y.$

Construction and equations

Construction of the bifolium

Given a circle C through a point O, and line L tangent to the circle at point O: for each point Q on C, define the point P such that PQ is parallel to the tangent line L, and PQ = OQ. The collection of points P forms the bifolium.

In polar coordinates, the bifolium's equation is

$\rho =a\sin \theta \cdot {\cos }^2\theta ,$

while (first eqn.)

${\rho }^{2\cdot 2}=a\cdot x^{2}y,{\rho }^2=\pm x\cdot (ay{)}^{1/2}.$

For a = 1, the total included area is approximately 0.10.

See also

• Folium of Descartes
• Trifolium curve

External links

• Bifolium at MathWorld by Wolfram