I am trying to find the correct equation to find the bearing off of true-north between two GPS coordinates. I have seen a lot of online calculators and a lot of formulas on this GIS stack exchange, but many of them give me different results! What is the most correct method?
It seems the most popular one is this method: Calculate bearing between two decimal GPS coordinates (Arduino / C++)
Another method is this one: Calculate bearing between two decimal GPS coordinates , but, I am getting completely different answers when using this method (off by like tens of degrees), and I can't even get a matching result on the example from that post: "I get 250.20613449 as expected."
On all of my attempts, I am consistently using the degrees notation for lat and lon (I'm not using the hours, minutes, second notation). Also, on all of my attempts, I swap the start/stop position of both coordinates and recalculate just to make sure I'm not solving relatively to the wrong start position.
Online calculators seem to give me a variance as well. Sometimes they match the first method, sometimes they don't.
Can someone help nip this in the bud, once and for all?
Here's an example prob we can focus on:
Start: 42.766698 -75.746404 Stop: 42.761405 -75.757653
If I plot these points on a map and guesstimate the bearing by eye: