CO-Ci2 CO-Orthoptic Circle
An orthoptic is the locus of points for which two tangents of a given curve meet at a right angle.
CO-Ci2 is the orthoptic of the reference conic.
The orthoptic of an ellipse x2/a2 + y2/b2 = 1, is the director circle x2 + y2 = a2 + b2.
The orthoptic of a hyperbola x2/a2 − y2/b2 = 1, a > b, is the circle x2 + y2 = a2 − b2.
The orthoptic of a parabola is its directrix.
