Excellent, , Quondum, and , though I think in the redirect a slightly larger discussion of the advantages of using tau would be helpful in understanding why anyone could have thought of a seemingly unorthodox mathematical proposal. The redirect already has the advantages of the notation of a turn in terms of tau (like a half revolution would be tau/2), but I believe a small discussion on the advantages on the sine function (like in this old Vi Hart video https://www.youtube.com/watch?v=jG7vhMMXagQ) would very much strengthen the argument. It doesn't have to be large. Or maybe that could appear on the sine page.