Not sure this will help any. But, I'll give it a shot.
Range finders don't normally shoot a pencil beam (which is really a cone with a narrow beam angle), rather they shoot a pie slice shaped beam. The beam angle is how wide the pie slice is (a 45 degree angle would be 1/8th of the pie, a 90 degree angle would be 1/4th of the pie).
The beam angle determines how wide the beam is at a given distance. You can think of it like MOA. If the beam angle is 1 MOA, it will cover 1 inch at 1 hundred yards, 2 inches at 200 yards, Etc. Equally, if the beam angle was 1 degree (60 MOA) the beam would be 60 inches wide at 100 yards and 120 inches wide at 200 yards.
Values are simplified because the fact that 1 degree results in the base of the triangle being 62.83 inches at 100 yards really does not matter here.