The diameter is the length from 1 point on the circle to another, going directly through the circle. A diameter is always 2 times the radius' length. Since the radius is 9 miles, we just need to multiply that by 2 to get the diameter. 9 x 2 = 18. Hope this helped!! :]
3cmx4models is the beginning to figure out how big the tallest. if you multiply 3 Centimeters (The smallest) by the amount of models (4) you would get 12 so thats you answer 12CM is the height so 4³