okay, man (or woman) stands on the equator and walks due east (or west) and every now and then he leaves a marker on the ground. after walking for several miles due east he turns around and with a pair of binoculars looks back the way he came at the markers he has left. If the earth really is a flat disc then the markers will not line up however if the earth is a sphere then they will line up (which is what is observed).
What your doing zeromatrix is showing that the Earth is spherical.
For instance you have 3 points all equidistant from each other on the Equator ,This is the greatest size circle you can draw on a sphere and in math its called a great circle.
In FE theory the shortest distance from one point to another is described by an isosceles triangle of 180°
The shortest distance on a sphere is also an isosceles triangle but in spherical geometry the sum of the angles of a spherical triangle is between pi radians and 3 pi radians so at a great circle you get a triangle of 540° , that is why the shortest distance along the equator is 180° or due East / West.
FE seems to say to travel the shortest distance, you (and everyone else) accidentally follow a curved route and take a longer path.
Hope this helps