\[\boxed{\mathbf{564.еуроки - ответы\ на\ пятёрку}}\]
\[\textbf{а)}\ a = 7\ см;\ \ h = 11\ см:\]
\[S = \frac{1}{2} \bullet ah = \frac{1}{2} \bullet 7 \bullet 11 =\]
\[= 38,5\ см^{2}.\]
\[\textbf{б)}\ a = 2\sqrt{3};\ \ h = 5\ см:\]
\[S = \frac{1}{2} \bullet ah = \frac{1}{2} \bullet 2\sqrt{3} \bullet 5 =\]
\[= 5\sqrt{3}\ см^{2}.\]
\[\textbf{в)}\ S = 37,8\ см^{2};\ a = 14\ см:\]
\[h = \frac{2S}{a} = \frac{2 \bullet 37,8}{14} = 5,4\ см.\]
\[\textbf{г)}\ S = 12\ см^{2};\ \ \ h = 3\sqrt{2}\ см:\]
\[a = \frac{2S}{h} = \frac{2 \bullet 12}{3\sqrt{2}} = \frac{8}{\sqrt{2}} = 4\sqrt{2}.\]