(If you're lost, you must have missed that last τ vs π video.)

This person marks a whole pie as τ/2, I suppose because a circle's area is πr², which is half of τr². Vi Hart marks a whole pie as τ (while a half-pie is π) because a full circle has an angular measure of τ (that is, 2π) radians. I prefer to think of the pies in terms of their area, because when someone asks, "But what do you eat on Tau Day?" I say that since τ is 2π, we eat twice as much pie!
