X(1), X(1022), X(1023)
feet of the antiorthic axis (inflexion points)
K228 is an isogonal circum-conico-pivotal cubic (See Special Isocubics §8.3). Compare K228 with K015, isotomic circum-conico-pivotal cubic.
K015 and K229 are two members of CL064.
It is an unicursal cubic with singularity at I (incenter). See also Table 69.
For any point M on K228, the line through M and its isogonal conjugate M* envelopes the circum-ellipse with perspector I, center X(9) the mittenpunkt. K228 is tritangent at A, B, C to this ellipse.