A sign giving the distance to several towns puts the reader on a circle around each of them. With two towns, the circles cross at two points; with three, only one is left. Choose the towns, enter the distances: the tool computes the point that best fits them.

In real life: radius circle tools (CalcMaps, Map Developers « Draw a circle »), used in geolocation with road signs, kilometre markers or hints like « 20 minutes from… ». Road distances are longer than straight-line ones: the point found is a search area, not an address.