Решебник по математике 9 класс. вероятность и статистика Высоцкий ФГОС Часть 2 Задание 198

\[\boxed{\mathbf{198.}}\]

\[\angle AOB = \angle COD = 60{^\circ};\]

\[\angle AOD = \angle BOC =\]

\[= 180{^\circ} - 60{^\circ} = 120{^\circ}.\]

\[S_{окр} = \pi R^{2}.\]

\[\textbf{а)}\ S_{BOC + AOD} =\]

\[= \frac{120}{360}\pi R^{2} + \frac{120}{360}\pi R^{2} = \frac{2}{3}\pi R^{2};\]

\[P = \frac{\frac{2}{3}\pi R^{2}}{\pi R^{2}} = \frac{2}{3}.\]

\[\textbf{б)}\ S_{\text{DOC}} = \frac{60}{360}\pi R^{2} = \frac{1}{6}\pi R^{2};\]

\[P = \frac{\frac{1}{6}\pi R^{2}}{\pi R^{2}} = \frac{1}{6}.\]