We went over this a few days ago (also it’s described in the article, in case you missed it). You are mistaken.
sin(pi) = sin(3.14...) = sin(tau/2)
cos(tau) = cos(6.28...) = cos(2 pi)
etc.
The sin and cos functions are functions of radians, and the arclength of a radian does not change when you start expressing a circle as 1 tau instead of 2 pi.
sin(pi) = sin(3.14...) = sin(tau/2)
cos(tau) = cos(6.28...) = cos(2 pi)
etc.
The sin and cos functions are functions of radians, and the arclength of a radian does not change when you start expressing a circle as 1 tau instead of 2 pi.