Radical axis

The radical axis of two circles is the set of all points that have equal power with respect to both circles. In other words, for any point on the radical axis, the difference between the squares of its distances to the centers of the circles equals the difference between the squares of the radii of the circles.

Important properties

• The radical axis is always a straight line.

• Every point on the radical axis has equal power to both circles.

• If the circles intersect, the radical axis passes through their intersection points.

• If the circles do not intersect, the radical axis still exists as a line.