A circle
The inches in a diameter = 2 X inches in the radius. Or, inches in a diameter = inches in circumference / pi
What is a "8 inch ball" ? Is 8 inches the diameter ? Then its diameter is 8 inches. Is 8 inches the radius ? Then its diameter is 16 inches. Is 8 inches the circumference ? Then its diameter is about 2.546 inches (rounded).
the diameter would be 7 inches
No. The Judge series are chambered for .45 Long Colt and .410-bore shotshells. That means a bore diameter of .454 inches, whereas the .30-06 has a diameter of .308 inches. In addition, the pressures would be unacceptable, and it's unlikely that an unrimmed .30-06 round would even chamber in a revolver.
Diameter = 117/pi inches
Twelve inches is a length. It can be a diameter, but if it is a diameter, you would simply say 'The circle is 12 inches diameter'. So; how big is it - it is 12 inches.
2 inches
14 inches in diameter
A circle 14 inches in diameter has a radius of 7 inches, and a circle having a radius of 7 inches has a diameter of 14 inches.
The diameter of the circle will be: 8.276 inches.
The diameter of the circle will be: 26.1 inches.
Diameter = 1.273 inches.