The bigger problem is anyone using trigonometry (instead of vector methods) in practical geometry code, where not absolutely necessary. If you go poking around

The bigger problem is anyone using trigonometry (instead of vector methods) in practical geometry code, where not absolutely necessary. If you go poking around geometric code (cartography, computational geometry, physics modeling, graphics, ...) and hunt for places where trigonometry is used, you’ll find lots of errors where the programmer didn’t consider the behavior in every edge case. The vector alternatives are simpler, more efficient, more numerically stable, and a lot easier to reason about.