ORD U4 - Radius is Calculated Incorrectly From Degree of Curve

If I enter the degree of curve when placing an arc, the calculated radius is incorrect.  For instance when I enter d1 (for a 1° curve), ORD returns a radius of 5729.589' rather than the correct value of 5729.578'. InRoads SS2 and both the legacy and civil geometry tools in InRoads SS4 return the correct values.