Concentric Constraint

Makes two arcs/circles concentric - sharing the same center point. You can also use this tool to place a point or endpoint at the center of a circle or arc.

1. Start with two arcs/circles. Activate the Concentric constraint and select the arc/circle you want to make concentric. This object will move to the second.
   
2. Select the second arc/circle.
   
   The first arc/circle moves, keeping its orientation, so that it is concentric with the second. The concentric constraint symbol (a plus sign) is added at the point of tangency.
   
   You can also use this tool on a point or line endpoint. Select a circle/arc and the point or endpoint. . .
   
   . . . and the circle/arc moves so that its center meets the endpoint or point.