Isn’t it a standard shape available in something like Word ?
Edit to add. A quick check says your numbers must be wrong. Your big R is 85mm, your small r is 75mm.
For a hexagon r = R x 0.866
That doesn’t quite work with your numbers. I’d just pick up the form in word. Print it out once, measure it, work out how much it needs scaling up or down, then scale it once and you’re done.