perpendicular_arc

perpendicular_arc(circle, circle1, circle2)

Return the circular arc inside circle that starts at circle ∩ circle1 and ends at circle ∩ circle2, and is perpendicular to all three circles.

Circles are given by (center, radius) pairs. The arc is constructed by inverting the midpoint of the endpoints through circle, which yields the center of the perpendicular circle; the shorter arc is returned. If the arc degenerates to a diameter, a segment is returned.