First puzzle on here.....I saw this recently and thought I'd post it here for all you math-minded individuals.

There was an answer provided (which I have verified by drawing it out), but this wasn't too satisfying and didn't give a proof!

So...

I have 3 circles (or cylinder, pipes, cigars if you like). Two lie just touching each other (with radii of 9 and 12cm), with their bases on the ground while the third rests on top so it touches both of them and its top is at the same height as the top of the largest circle.

What is the maximum diameter of the little circle at the top? Can you prove it?

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First puzzle on here.....I saw this recently and thought I'd post it here for all you math-minded individuals.

There was an answer provided (which I have verified by drawing it out), but this wasn't too satisfying and didn't give a proof!

So...

I have 3 circles (or cylinder, pipes, cigars if you like). Two lie just touching each other (with radii of 9 and 12cm), with their bases on the ground while the third rests on top so it touches both of them and its top is at the same height as the top of the largest circle.

What is the maximum diameter of the little circle at the top? Can you prove it?

Enjoy....

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