The formula for circumference is 2 x Pi x R, or Pi x D. The standard number for Pi is 3.14.
Our current circumference is 88cm, and we're looking for the diameter.
Since we are looking for the diameter, we need to reverse the equation. By doing this we need to divide by 3.14, as our current formula is now:
88 = 3.14 x D.
To find D, the Diameter, we need to divide by 3.14.
88 / 3.14 = 28.025 or rounded, 28.03cm.
Your diameter is 28.03cm.
I hope this helps!