(a) If we consider the intersections of the circle Hi(O) (center Hi and radius HiO) with the line Ai+1Ai+2, then we obtain six points which all lie on a circle with center H (first Droz-Farny circle). (b) If we consider the intersections of the circle Mi(H) (center Mi and radius MiH) with the line AiAi+1, then we obtain six points which all lie on a circle with center O (second Droz-Farny circl...
