Constrains the the radius of a circle, an arc, or polyline arc segment. (This command is equivalent to the Radius option of the DIMCONSTRAINT command.)
Accessing the Command
command bar: dcradius
menu bar: Parametric  2D Constraints  Radius
toolbar: 2D Constraints 
ribbon: Parametric  2D Constraints  Radius
: dcradius
Prompts you in the command bar:
Select arc, circle or curved polyline segment: (Select a circle, arc or polyline arc segment)
Specify dimension location: (Select a point to position the dimension line)
Dimension text <xx.xx>: (Type a value, or else press Enter to accept the current value)
The radius of the entity is now constrained, although the entity can still be moved, rotated, and so on.
Command Options
Option 
Description 
Select arc, circle or curved polyline segment:

Select one:

Specify dimension location  Move the cursor, and then pick a point to position the dimension line 
Dimension text <xx.xx> 
Choose one:

Procedures
Related Commands
Dimconstraint  applies a dimensional constraint to an entity or between constraint points on entities; converts associative dimensions to dynamic dimensions.
Geomconstraint  applies geometric relationships between entities and/or valid constraint points on entities.
DcAligned  constrains the distance between two points.
DcAngular  constrains the angle between two lines or linear polyline segments; the total angle of an arc or an arc polyline segment; or the angle between three points on entities.
DcConvert  converts an associative dimension to a dimensional constraint.
DcDiameter  constrains the diameter of a circle or an arc.
DcHorizontal  constrains the horizontal distance (Xdistance) between two points with respect to the current coordinate system.
DcLinear  constrains the horizontal distance (Xdistance) or vertical distance (Ydistance) between two points with respect to the current coordinate system.
DcVertical  constrains the vertical distance (Ydistance) between two points with respect to the current coordinate system.
ConstraintBar  controls the display of the constraint bar of entities.
DcDisplay  allows to set dimensional constraints to be displayed or hidden.
Delconstraint  removes all dimensional and geometrical constraints from an entity.
CleanUnusedVariables  purges variables not used in constraint expressions and not linked to dimensions.
Parameters  manages 2D dimensional constraint parameters and user variables in the current drawing.