[tex]e = 20 \ cm\\f = 10 \ cm\\P = ?\\Obw = ?\\\\Pole:\\\\P = \frac{e\cdot f}{2} = \frac{20 \ cm\cdot10 \ cm}{2} = 100 \ cm^{2}\\\\Obwod:\\\\P = a^{2}\\\\a^{2} = 100 \ cm^{2}\\\\a = \sqrt{100 \ cm^{2}}\\\\a = 10 \ cm\\\\Obw = 4a = 4\cdot10 \ cm = 40 \ cm[/tex]
