\[1)\ S_{n} = 1080{^\circ}:\]
\[S_{n} = (n - 2) \bullet 180{^\circ} = 1080{^\circ}\]
\[n - 2 = 6\ \ \]
\[n = 8 \in N.\]
\[Ответ:\ \ да.\]
\[2)\ S_{n} = 1200{^\circ}:\]
\[S_{n} = (n - 2) \bullet 180{^\circ} = 1200{^\circ}\]
\[n - 2 = 6\frac{2}{3}\ \]
\[n = 8\frac{2}{3} \notin N.\]
\[Ответ:\ \ нет.\]