This is a more general
specimen of the right strophoid.
Now the line OO' through pole O and fixed point O' is no longer perpendicular to the
construction line l.
The parameter a = π/2 for the right strophoid can now also have other values,
in Cartesian coordinates: x3 + x y2 - x2 + y2 =
y (x2 + y2 - 2x) cotan a
The curve is a pedal of the parabola, and a special
case of the general strophoid. Sometimes the
oblique strophoid itself is called the 'general strophoid'.