Edit Bar control: Ok
This tool adds a cocircular constraint between two arcs.
To use the tool, identify two arcs. You can also hold the Shift key down whilst identifying them to include more arcs. When you have finished identifying them the arcs will be constrained so that they all have the same centre point and same radius. There could be gaps or overlaps between adjacent arcs.
Note that the effect of applying a cocircular constraint is identical to the combined effect of a concentric constraint and an equal radius constraint.
After creating the cocircular constraint you can hover your cursor over the constraint and all related entities will be highlighted.
Shift Modifier
You can also hold the Shift key down whilst identifying them to include more arcs. When you have finished identifying them, all arcs will be included in the constraint.
After identifying two arcs whilst using the Shift modifier the Ok button becomes active on the edit bar: 
You can now click this button to finish the tool and apply the constraint.
Pre-selected Entities
Alternatively, you can select two or more arcs and then start the tool. The cocircular constraint will then be added to all selected arcs.
NOTE: Whilst this tool can be used to move entities so as to satisfy the constraint, it is recommended that entities are created in the desired position.