Yes, because that's not abusable in the least.

It isn't complicated at all and it is rare that you have to check more than two spots. Knowing how to do the math in general is much simpler than having to keep a printout of a chart (or the contents of your post) on hand that people have to reference while they try and walk squares.

Not complicated for who? I agree that people like you, me, and a number of others could manage, but I'd be willing to bet >50%(probably much more) of the HC population couldn't perform Trig calculations in their head, and even those that could, it would likely take less time to look up a reference and walk the squares than to perform those calculations, even if there were only 1 or 2 points to check. I'm not saying this is for everyone, I don't personally have this chart printed out, I can get by just fine without it. I was just offering it as a tool for others that may find value in it. And considering it's common to carry around a string for LOF, or a PAC/Rulebook/TA List/etc. for referencing, a simple chart isn't that much overhead.

Again, one of the hardest things to understand is that everyone doesn’t understand things the same way.
This sometimes makes arguments of “the best way” futile.
I have my best way. It’s easy for me. It never fails me.

But bringing forth all these ways of determining line of fire is important and I applaud all who have shared thus far. The more tools we have, the better.

I claim my method never fails. But sometimes that only convinces me. I still need a way for the other players to see I’m right. So using another method as proof gives them understanding of my method, and an additional tool for their clixing as well