The title says it all.
This info could be handy at time.
What would be nice is if the two fields could be editable, either the Radius or the Diameter.
It could also be added for polygons too.
I think two fields would be redundant. However the radius field could allow simple mathematical operations, e.g. "4m*2". Implementing mathematical operations in length parsing would of course also apply to the VCB and any other length input.