That is that you have two points. And all of those geometries including the Euclidean geometry all define distances that are logical and consistent and hold all the properties that are expected for a distance. This is the base with a distance of 3 units.
If the coordinates of the two points are x1 y1 and x2 y2 the distance equals the square root of x2 x1 squared y2 y1 squared.
The formula is a2 b2 c2. That is that you have two points. M M R where R denotes the set of real numbers that satisfies the following conditions. Although it is not a static or universal concept as there many potential measures of distance in Math.