Every isosceles triangle has an axis of symmetry along the perpendicular bisector of its base. A chord's perpendicular bisector passes through the center of the circle and bisects the angle. Its perpendicular bisector is another chord, which is a diameter of the circle. Another chord is the perpendicular bisector of and is consequently a diameter of the circle. So the perpendicular bisector of D'D (a segment of s) is also perpendicular to r. A line segment bisector passes through the midpoint of the segment. The mirror is mounted so its reflective surface is perpendicular to this bisector. Each point of an angle bisector is equidistant from the sides of the angle. There exist integer triangles with a rational angle bisector. Angle "CMD" is bisected, and the bisector intersects the vertical axis at point "Q". The centers of the circles in this pencil lie on the perpendicular bisector of "CD". No two non-congruent triangles share the same set of three internal angle bisector lengths. Line formula 199 is the bisector of the angle between the lines formula 193. The intersection of the circles (two points) determines a line that is the angle bisector. A standard textbook method is to construct the bisector of the angle at A.