I am currently working to understand a combinatorics problem. Within the proof they state that "Two circles can have at most one common chord ..." and I do not understand why this is true. I've included a screenshot from my textbook.
The book then goes on to finish the proof. Now I can follow everything before the last paragraph, but have no idea why two circles can have at most one common chord (last full sentence of last paragraph).
Question: Can you please provide some explanation for why two circles can have at most one common chord?