To specify the radius of a circle:
| 1. | Make sure you're in select mode  and click the circle. The circle will be highlighted as well as the icon  . |
| 2. | Click the Radius icon, enter the constraint value, either real or symbolic, and press enter. You can press enter without typing a value to let the system insert a variable name. |
You can click the constraint and drag it to adjust its placement on the drawing.