? contains a cardinality smaller sized than or equal for the cardinality of A different established ? T displaystyle T ? along with the set of all true numbers possess the exact same cardinality, a bijection getting provided by the operate ? x ? tan ? ( ? x / 2 ) displaystyle xmapsto tan(pi x/two) D?ch trong m?i ?ng d?ng B?t k? b?n ?ang dùng ?ng d