Anyone know how to calculate the radius of a plane?
I Googled it, but could not find an answer.
Rectangles don’t have radii, what are you talking about…
Somebody better tell Blender !
And how the heck did this get moved to ‘Python Support?’
good find 
Looks like it’s mislabeled, should probably be called “Scale”
That’s just a symbolic name they used which represents the radius of a circle inside a square:
A rectangle can’t have a radius because if you draw a line from the center you’re going to get different lengths depending on which part of the rectangle they intersect. If you want to know the length of a diagonal, you’ll have to think of it as the hypotenuse of a right-triangle and figure out the length using its legs. Since you know both of those lengths you use c=√(a²+b²)
All I really wanted was for someone to take the bait. 
So… Thanks!
I feel like a tool now 