Take the intersection point C of the ray BD with the circle C, see Figures 5 and
6. Connect the point C with an arbitrary point A on the circle C (different from
C) and let h be the ray obtained by reflecting the ray AD in the line AC. The ray
h cuts the ray BC in a point E by Lemma 1 which is the inverse point of D with
respect to the circle C in view of Theorem 2.