Open and Closed Balls in Euclidean Space Mathonline
Notice the subtle difference between the definition of an open ball and the definition of a closed ball. The only difference between an open ball in mathbb{R}^n and a closed ball in mathbb{R}^n is that closed balls contain all quot;exteriorquot; points while open balls do not., a closed ball in mathbb{R}^3 centered at mathbf{a} with