I think you mean circumference, which is equal to = 2πr
The solution would be like this for this specific problem:
√512m³ = √256m² × √2m
= 16 × √2m
I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.
If you know the measurements of 2 sides not the height , you can apply Pythagorean theorem to find the height. Square root of the sum of the squared sides