Cartesian equation:
y2(x2 + y2) = a2x2
Polar equation: r = a cot(θ)
Click below to see one of the Associated curves.
The curve was studied by Newton and, some years later, by Johann Bernoulli.
The URL of this page is:
http://www-history.mcs.st-andrews.ac.uk/Curves/Kappa.html