Thank you for the opportunity to help you with your question!
Diameter can be go through the following formula
D=√ 4v/hr pie SO. The volume (πr²h) is 289. We know the height is 21cm Therefore... 289 = πr² * 21 πr² = 289 / 21 r² = 289 / (21π) r = √(289 / (21π)) The diameter is twice the radius, so... d = 2√(289 / (21π))
Please let me know if you need any clarification. I'm always happy to answer your questions.