\[\boxed{\mathbf{365\ (365)}.\ Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ a = 14\ см = b + 5\ см\]
\[b = 14 - 5 = 9\ см.\]
\[P_{пр} = 2 \cdot (a + b) =\]
\[= 2 \cdot (14 + 9) = 2 \cdot 23 = 46\ см.\]
\[2)\ P_{пр} = 34\ см;\ \ a = 12\ см.\]
\[P_{пр} = 2 \cdot (a + b) = 34\]
\[2 \cdot (12 + b) = 34\ \ \]
\[12 + b = 34\ :2\]
\[12 + b = 17\]
\[b = 17 - 12 = 5\ см.\]
\[Ответ:\ \ 1)\ P_{пр} = 46\ см;\ \ 2)\ b =\]
\[= 5\ см.\]