\[Схематический\ рисунок.\]
\[AC = 8\ см;BD = 12\ см;\angle BOA = 30{^\circ}:\]
\[S = \frac{1}{2} \bullet AC \bullet BD \bullet \sin{\angle BOA} =\]
\[= \frac{1}{2} \bullet 8 \bullet 12 \bullet \sin{30{^\circ}} =\]
\[= 48 \bullet \frac{1}{2} = 24\ см^{2}.\]
\[Ответ:\ \ 24\ см^{2}.\]