A fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock-mass movement.
Idk if this will help but...
In geometry, parallel lines are lines in a plane which do not meet; that is, two lines in a plane that do not intersect or touch each other at any point are said to be parallel. By extension, a line and a plane, or two planes, in three-dimensional Euclidean space that do not share a point are said to be parallel.
You would take a ruler and measure the amount of centimeter or inches between the two places. Then measure the scale. If the scale was 50 miles and 1 inch and the two points were 2 inches apart. The places would be 100 miles apart because 50*2=100