\[\boxed{\mathbf{298.}ОК\ ГДЗ\ –\ домашка\ на\ 5}\]
\[Дано:\]
\[ABCD - квадрат;\]
\[AA_{1} = b;\]
\[сторона\ квадрата = a.\]
\[Найти:\ \]
\[S_{пов}.\]
\[Решение.\]
\[1)\ AC^{2} = 2a^{2};\]
\[AC = a\sqrt{2};\]
\[AO = \frac{a\sqrt{2}}{2}.\]
\[2)\ A_{1}M^{2} = \frac{a^{2}}{4} + b^{2} - \frac{a^{2}}{2} =\]
\[= b^{2} - \frac{a^{2}}{4}.\]
\[3)\ S_{бок} = 4 \cdot a\sqrt{b^{2} - \frac{a^{2}}{4a}} =\]
\[= 2a\sqrt{4b^{2} - a^{2}}.\]
\[S_{пов} = 2a^{2} + 2a\sqrt{4b^{2} - a^{2}}.\]
\[Ответ:\ 2a^{2} + 2a\sqrt{4b^{2} - a^{2}}\text{.\ }\]