Approximately 8 inches, BECAUSE the formula for the circumference of a circle is pi, (known as 3.14), times the diameter, OR pi times radius times 2. (A radius is half of a diameter, so you add them twice to get the diameter. Example: radius = 2 You will do 2 + 2 to get the diameter as 4.) Now, in this problem, we have to divide the circumference by the exact number we have left, which is pi, (3.14). 26 divided by 3.14 = 8.28.....(continuing). So the diameter is approximately 8 inches. :-)