Answer:
20π m or 62.83 m
Explanation:
The formula for Circumference is C = 2πr
All you need to find for the formula is the radius, which is half of the diameter.



Then plug the radius into the formula and solve for Circumference


or 
What are you talking about?
Answer: Cadê o texto?
Explanation: A escrita em português de Portugal é mais formal e confusa o português BR é mais fácil de ser entendido.
Sorry i don't understand..