There are 360 degrees in a circle. If your wedge tool is 10 degrees, you would need 36 blades.
You can use 12 degrees for 30 blades.
Or 15 degrees for 24 blades.
Or 18 degrees for 20 blades.
Or 20 degrees for 18 blades.
Or 22.5 degrees for 16 blades.
Or 45 degrees for 8 blades.
Looks like the circle is sewn into the background fabric either with the set-in circles or reverse applique. Looks like the top circle is appliqued on top.
Here are a couple tutorials for sewing "set-in circles."
https://www.youtube.com/watch?v=EzWJZjQLt5E
and:
https://www.youtube.com/watch?app=desktop&v=vxERXM3-6lQ