How to Layout a Wiinding Stair
Laying out a winding stair using compass dividers and a straight edge.
9 winding Treads in 180 degrees= 20 degrees per tread.
Math 12" radius x PI= 37.7" in 180 degrees. Divide x 9 treads = 4 7/8"+ per run.
By using Compass dividers the same solution can be had without using math.