Definition:Cissoid of Diocles

Definition
The cissoid of Diocles is the plane curve defined in Cartesian coordinates as:
 * $x \paren {x^2 + y^2} = 2 a y^2$

or in polar coordinates as:
 * $r = 2 a \sin \theta \tan \theta$

for some real constant $a \in \R_{> 0}$.


 * CissoidOfDiocles.png

The above diagram illustrates the cissoid of Diocles.

Also known as
Some sources refer to the cissoid of Diocles as merely a cissoid, but that term is best used to refer to the more general object of which the cissoid of Diocles was the original instance.