From FreeCAD Documentation
- Optionally specify the line attributes with the TechDraw ExtensionSelectLineAttributes tool.
- Select the first vertex to determine the center point of the arc.
- Select the second vertex to determine the radius and the start angle of the arc.
- Select the third vertex to determine the end angle of the arc.
- There are several ways to invoke the tool:
- Press the Add Cosmetic Arc button.
- Select the TechDraw → Extensions: Centerlines/Threading → Add Cosmetic Arc option from the menu.
- A cosmetic arc is added.