Thus, to locate an electric light at a point eighteen feet from the point of intersection of two streets and equidistant from them, evidently one locus is a circle with a radius eighteen feet and the center at the vertex of the angle made by the streets, and the other locus is the Bisector of the angle.
"The Teaching of Geometry"
David Eugene Smith
Thus in the case of the locus of points in a plane equidistant from two given points, it is sufficient that the point be on the perpendicular Bisector of the line joining the given points, and this is the first part of the proof; it is also necessary that it be on this line, i.
"The Teaching of Geometry"
David Eugene Smith