# Definition(s)
> [!NOTE] Definition 1 ()
> The closed ball of radius $r>0$ *centered* at $a\in \mathbb{R}^n$ is given by $\overline{\mathbb{B}_{r}(a)}:=\{ x\in \mathbb{R}^n : \Vert x-a \Vert \leq r \}.$
Note: We may write $\overline{\mathbb{B}_{r}(a)}$ instead of $\overline{\mathbb{B}(a,r)}$.
> [!Example] Example
> Contents
# Properties(s)
# Application(s)
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# Reference(s)