Locus

In some cases, a locus may be defined by more that one distinct set of conditions. In this case the locus is called a compound locus, and corresponds to the intersection of two or more loci. For example, the locus of points that are equidistant from two given points and also equidistant from two given parallel lines (Figure 1c), is a single point. That point lies at the intersection of two lines, one line containing those points equidistant from the two points, and one line containing all those points equidistant from the parallel lines.