222. When using GPS, how many theoretical position lines are required for a two-dimensional fix?

Three position lines from GPS satellites are required to determine a two-dimensional fix, resolving both position and receiver clock error. Each satellite provides a line of position; two lines result in ambiguous intersection points, while three lines produce a unique horizontal position (latitude and longitude). While four satellites are used for a full three-dimensional solution, the question specifically addresses the theoretical minimum for a two-dimensional fix.