\[\boxed{\mathbf{735\ (735).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ l = 18,84\ см:\]
\[l = 2\pi r \Longrightarrow \ \ \ \ r = \frac{l}{2\pi} = \frac{18,84}{2\pi} =\]
\[= \frac{9,42}{3,14} = 3\ см.\]
\[2)\ l = 47,1\ дм:\]
\[l = 2\pi r \Longrightarrow \ \ \ r = \frac{l}{2\pi} = \frac{47,1}{2\pi} =\]
\[= \frac{23,55}{3,14} = 7,5\ дм.\]