oblique strophoid


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'.