\[\boxed{\mathbf{471.ОК\ ГДЗ - домашка\ на}\ 5}\]
\[Рисунок\ по\ условию\ задачи:\]
\[\mathbf{Дано:}\]
\[\mathrm{\Delta}\text{ABC} - прямоугольный;\]
\[\textbf{а)}\ \text{AC} = 4\ см;\]
\[\text{BC} = 11\ см;\]
\[\textbf{б)}\ \text{AC} = 1,2\ дм;\]
\[\text{BC} = 3\ дм.\]
\[\mathbf{Найти:}\]
\[S_{\text{ABC}} - ?\]
\[\mathbf{Решение.}\]
\[\textbf{а)}\ S_{\text{ABC}} = \frac{1}{2} \bullet \text{AC} \bullet \text{CB} =\]
\[= \frac{1}{2} \bullet 4 \bullet 11 = 22\ см^{2}.\]
\[\textbf{б)}\ S_{\text{ABC}} = \frac{1}{2} \bullet \text{AC} \bullet \text{CB} =\]
\[= \frac{1}{2} \bullet 1,2 \bullet 3 = 1,8\ дм^{2}.\]
\[Ответ:а)\ 22\ см^{2};б)\ 1,8\ дм^{2}.\]