Causes selected objects to become symmetrically constrained about a selected line.

Button
Ribbon: Parametric tab
Geometric
panel
SymmetricNot available on the ribbon
in the current workspace
Menu: Parametric
Geometric
Constraints
SymmetricNot available in menus
in the current workspace
Toolbar: Geometric
Constraint
This command is equivalent to the Symmetric option in GEOMCONSTRAINT.
For lines, the line’s angle is made symmetric (and not the endpoints). For arcs and circles, the center and radius are made symmetric (not the endpoints of the arc).
Following are the valid constraint objects and points: