4 ms·

Do you mean the advantage of writing pi*d for the circumference instead of tau*r or tau*d/2? I wouldn't keep pi around just for this...

• rmunn 10mo ago
  Yes, though more broadly my point was that the radius is the natural measurement of the circle for most things since most things are center-based. But for some physical measurements, mostly based around pipes, "what is the width of this pipe" is the question you need answering, and that is diameter-based. And pi is circumference/diameter, while tau is circumference/radius. But yes, if the world switched to tau then you wouldn't need pi anymore, you'd just write tau/2 in the rare cases where having the circumference/diameter ratio handy is useful.