Recently got kitchen remodeled and have several island corners with differing radius'. Decided to hit home depot/lowes and buy a piece of XPS 1" foam board, and cut to dimensions and see. My island was 60X39 with (2) 10" radius and (2) 4" radius.

for the 10" radius, mark 10" from either edge, and where they meet is the center of the radi (circle). Trace with edge of tape measure using metal edge to mark the curve. Cut with steak knife. 4" radius just requires the 4" measurement from the edge, the trace with the tape measure with 4" on the intersection. (see 2nd image).

Start with smaller radius and shave down to appropriate as needed (last pic).

Takes the guess work out on a major purchase like this.

Hope this helps.