Probably has no practical application. And probably already exists in other/simpler forms. Given a circle w/ known radius; determine the side length of and equilateral triangle. surrounding circle tangent at 3 points. Am i good or what?

I know of a formula to find inradius of any triangle, but it is a one way function since it involves adding side lengths: inrad= area/(a=b=c/2)
works for any triangle. Non reversible.
My method finds inrad of equilateral triangles(working on tweaking it to work for any triangle) and is reversable.
So how useless is my discovery and how many times has it been done before?

note:im not sharing the formuoli. Just explaining what it does to hear how un important and a repeat discovery it is(I assume).