Szczegółowe wyjaśnienie:
[tex]a = 20cm\\Ptrojkata=\frac{a^{2}\sqrt{3}}{4} \\P = \frac{20^{2} * \sqrt{3}}{4} = \frac{400*\sqrt{3}}{4} = 100\sqrt{3}cm^{2} \\Ptrojkata = Pprostokata[/tex]
[tex]Pprostokata = a*b\\a = 2,5dm = 25cm\\100\sqrt{3} cm^{2} = 25 cm *b / :25\\b = 4\sqrt{3}cm[/tex]
