[0WT]Show that two balls \(B(x,r)\) and \(B(y,r)\) of equal radius are disjoint or are coincident; in particular they are coincident if and only if \(y∈ B(x,r)\). Similarly for the discs \(D(x,r){\stackrel{.}{=}}\{ y∈ X : d(x,y)≤ r\} \) and \(D(y,r)\).
