Creating a circle with a given radius

[hilaire]

The documentation is not clear enough to explain how to create a circle with a given radius.
See this user question:

"Hey there ! I’m trying to create, in Dr. Geo, a vesica pieces. Think Venn diagram. It is two circles whose centers are the points of radius for the other circle. I am, however, having quite the time constructing this. The documentation says it is possible to create a circle with entering a radius value, however I’m not sure how to do this. So on the grid, how would I create a circle with a radius of 4, and another circle overlapping it?

In other words, how do I enter the values Directly where the center and radius are? With the line segments, it gives you an x and y axis to change. How do i do this with circles, instead of just scaling it with the mouse (as that is very inaccurate)?"

[hilaire (hilaire-fernandes)]

Proposed addition to the circle documentation:

"
To create a circle from its center and radius, you need a point and a value. The value must exist prior to the circle. It can be any sort of value: a computed one like a distance or a free value you edit. You create a free value from the "Numerics" tool (ref. to http://drgeo.olympe.in/doc/en/drgeo004.html#@default34)
"