When the runner exit the nether, most of runner throw an eye. For exp, an eye showed straight ahead and runner go left and throw an eye again. This way it measures angle. I always do it. But I have a question. How can runner says "1000 blocks away" ? When you see angles doesn't change, you can say "it's far away " but how can they say with numbers?

1. the angle cant be the same unless ur at like 100000, 100000
2. first angle minus the second angle/1000 equals the approximate distance to the stronghold

as leafpoolsr said, it's the 1st - 2nd / 1000 for example 163 - 160 is a 3 degree angle change so it's roughly 300 blocks away I'm not sure if I'm allowed to send links but I made this video to show you.