The diameter is the supremum of the distances between pairs of points of the set.Suggest a slogan
Let \((X, d)\) be a metric space and let \(A\subseteq X\) be nonempty. The diameter of \(A\) is \[ \diam(A) = \sup_{x, y\in A} d(x, y)\in[0,\infty]. \]
What is the diameter of set?