STROPHOID

Angle trisection curve

Right strophoid:
x = a(t²−1)/(t²+1), y = at(t²−1)/(t²+1)
y² = x²(a+x)/(a−x)

Trisects angle at O via
intersections of secants
Node at origin. Asymptote x=a.
Loop for x∈[−a,0].