So in the math world there is a lot of eye-rolling and sighing over the Tau proposals and a vocal minority that argues adamantly for those proposals.
I just want to say that it doesn’t have to be either/or. Introducing tau (τ) for one turn (2π) would’ve made learning and understanding trig much easier back when I was a teen and learning this stuff for the first time. A curriculum or textbook based on tau, that also mentions that pi is half tau (or vice versa), would’ve been awesome.
When we were young, we were taught that the circumference of a circle was π × ⌀ (and our textbook erroneously referred to that diameter symbol as “phi”, well, half erroneously because it used an upright phi, “Φ”). This was used for a little while then promptly discarded and for the rest of our schooling we had “r” and “2r” instead, radius instead of diameter.
Math scientists and workers all around the world, they don’t need to worry about losing their beloved π. Every serious math nerd already know that they are free to define and discard whatever constant they need for the problem at hand. But textbook writers for kids and teens, please consider using τ. All of the sine cosine etc etc business becomes much more confusing with a turn being 2π radians instead of τ radians. For the cases where π is better, use it. For the cases where τ is better, use it.
It’s easier for students when the variables are clearly defined and packaged up. A 2π formula is more confusing than a τ formula. That’s why we extract methods and variables in programming, to get an easier handle on the stuff we’re throwing around, mentally.
I use and love tau, it’s great, but there are also cases where pi is more elegant. That’s why we can use both, or, use the one of the two that makes the most sense in a given context.