You add the circumference and the diameter to get the radius

It's the distance from the centre to any corner i.e. Half the diagonal. Weird terminology.

I'm looking for the same answer with same exact area! Did you ever happen to find the answer? Pleaseeee let me know

If the area of the square is 72 in square, find the radius

I don't think that a square has a radius, an area sure but no radius