Insert
ProfileCollinearity
The Collinearity Constraint command enables you to constrain two entities in a 2D profile or a 3D profile so that they align with each other. The constraint can be applied on lines and arcs.
When assigning a Collinearity constraint to two lines, one of the lines can be an external entity. In case of arcs, the constraint makes them of equal radii and concentric.
To apply the constraint, after starting the command, simply click on the two entities. The program immediately applies the constraint and adds the 
identifier.
Note that the program determines which entity to move based on the other constraints on the profile. If there are no constraints, the program moves the entity that produces the least change to the profile. When one of the entities is an external entity, the external entity remains fixed.
