Réponses

2013-02-11T17:53:34+01:00

Si les rapports des longueurs largeur / longueur sont les mêmes alors L/l = l/L-l

ou l/L = L-l/l => L/l = L/l -1 =  soit L/l = x => 1/x = x - 1 => 1 = x² - x  => x² - x - 1 = 0

(x-1/2)² = x² - x + 1/4

x² - x - 1 = x² - x + 1/4 - 5/4 = (x-1/2)² -5/4 = 0 => (x-1/2) = -V5/2 => x = (1-V5)/2

                                                                        ou  (x - 1/2) = V5/2 => x = (1+V5)/2