bonjour
AB = x cm
EB = 6 cm
AE = x - 6
AD = x
aire ADE =[ x / (x - 6 )] / 2 = ( x² - 6 x ) / 2 = 0.5 x² - 3 x
aire ABCD = x²
x² = 4 ( 0.5 x² - 3 x )
x² = 2 x² - 12 x
x² - 2 x² - 12 x = 0
- x² - 12 x = 0
x ( - x + 12 ) 0
x = 0 ou 12
0 non retenu ici donc x = 12