A First Course in Complex Analysis · Problem 7.5.15

Taylor and Laurent Series — Beck, Marchesi, Pixton & Sabalka

Mathematics — Complex Analysis · least-upper-bound

Problem

Find the least upper bound of the set

\left\{\operatorname{Re}\left(e^{2\pi i t}\right) : t \in \mathbb{Q} \setminus \mathbb{Z}\right\}