About the Project Command
Use the Project command to create geometry by projecting selected model curves or edges onto the sketching plane. The system aligns endpoints of the entity to the endpoints of the edge. The entity created has the 
constraint symbol.
constraint symbol.After you create geometry by projecting a curve or an edge, you can use the Trim, Divide, and Fillet tools to modify the geometry.
Note the following selection restrictions:
• A circle is broken into two arcs. You can select each segment separately, or use chain selection.
• To select a composite datum curve, use Query Sel or right-click a few times until it highlights.
• You cannot select the silhouette edge of a spline.
• You can orient the model any way.