Given curves C1 and C2 and a fixed point O. Draw
lines l through O that intersect C1 in Q1, and C2 in Q2. Then the cissoid
is defined as the collection of points P (on l) for which OP is equal to the distance
between the intersections (Q1Q2).
Some special cases of the cissoid:
The first cissoid to be discovered was the cissoid of