Definition:Cissoid of Diocles

Definition
Let $C$ be a circle of radius $a$ with a distinguished point $O$ on its circumference.

Let $L$ be the tangent to $C$ at the other end of the diameter of $C$ through $O$.

Let $R$ be a point on the circumference of $C$.

Let $OR$ be produced to meet $L$ at $S$.

Let $P$ be the point on $OS$ such that $OP$ = $RS$.

The cissoid of Diocles is the locus of points $P$ as $R$ travels around the circumference of $C$.


 * CissoidOfDiocles.png

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.

Also see

 * Equation of Cissoid of Diocles