Can anyone advise on how to calculate the angle between two points?

For example the angle between 160,0 and 160,160 would be 0 degrees.

My research into this has all found that the function acos() is required https://byjus.com/angle-between-two-vectors-formula/. This page talks about atan2() https://stackoverflow.com/questions/2676719/calculating-the-angle-between-the-line-defined-by-two-points

There is another way using Diamond Angles but there are various thoughts on whether it will work for us https://stackoverflow.com/questions/1427422/cheap-algorithm-to-find-measure-of-angle-between-vectors

Has anybody successfully calculated angles in the free version?

Thanks

Dave