[tex]Obw\,od\ \ kwadratu=4a\\\\4a=\frac{4}{9}\ \ |:4\\\\a=\frac{4}{9}:4\\\\a=\frac{\not4^1}{9}\cdot\frac{1}{\not4_{1}}\\\\a=\frac{1}{9}\\\\Wz\'or\ \ na\ \ przekatna\ \ kwadratu\ \ d=a\sqrt{2}\\\\d=\frac{1}{9}\sqrt{2}\\\\Odp.Dlugo\'s\'c\ \ przekatnej\ \ kwadratu\ \ wynosi\ \ \frac{1}{9}\sqrt{2}[/tex]
