\[\boxed{\mathbf{548.еуроки - ответы\ на\ пятёрку}}\]
\[\textbf{а)}\ a = 8,5\ см;b = 3,2\ см:\]
\[S = 8,5 \bullet 3,2 = 27,2\ см^{2}.\]
\[\textbf{б)}\ a = 2\sqrt{2}\ см;b = 3\ см:\]
\[S = 2\sqrt{2} \bullet 3 = 6\sqrt{2}\ см^{2}.\]
\[\textbf{в)}\ S = 684,8\ см^{2};a = 32\ см:\]
\[b = 684,8\ :32 = 21,4\ см.\]
\[\textbf{г)}\ S = 12,5\ см^{2};b = 4,5\ см:\]
\[a = 12,5\ :4,5 = 2,7\ см.\]