ГДЗ по геометрии 9 класс Мерзляк Задание 175

\[1)\ a = 72{^\circ}:\]

\[S_{n} = (n - 2) \bullet 180{^\circ} = n \bullet 72{^\circ}\]

\[n - 2 = \frac{2}{5}\text{n\ }\]

\[\frac{3}{5}n = 2\ \ \ \]

\[n = 3\frac{1}{3}.\]

\[Ответ:\ \ нет.\]

\[2)\ S_{n} = 171{^\circ}:\]

\[S_{n} = (n - 2) \bullet 180{^\circ} = n \bullet 171{^\circ}\]

\[n - 2 = \frac{19}{20}\text{n\ \ }\]

\[\frac{1}{20}n = 2\ \ \]

\[n = 40.\]

\[Ответ:\ \ да.\]