Дано S - 30cм(квадратных) P - 26см. найти стороны прямоугольника а.б.с.д

[latex] \left \{ {{30=ab} \atop {26=2(a+b)}} \right. [/latex] [latex] \left \{ {{30=ab} \atop {13=a+b}} \right. [/latex] [latex] \left \{ {{30=ab} \atop {a=13-b}} \right. [/latex] [latex]30 = (13-b)*b [/latex] [latex]30 = 13b - b^{2} [/latex] [latex]13b - b^{2} - 30 = 0[/latex] [latex]- b^{2} + 13b - 30 = 0 [/latex] [latex]b^{2} - 13b + 30 = 0 [/latex] [latex]D = 169-4*1*30 = 169 - 120 = 49 [/latex] - по формуле D = b² - 4ac [latex]b1 = \frac{-b- \sqrt{D} }{ {2a} } = \frac{13-7}{2} = \frac{6}{2} = 3[/latex] [latex]b2 = \frac{-b+ \sqrt{D} }{2a} = \frac{13+7}{2} = 10[/latex] 30 = a1b1 a1 = 30:3 = 10 30 = a2b2 a2 = 30:10 = 3 ОТВЕТ: 3, 3, 10, 10