bonsoir
AB = 600 m
BC² = 600² + 450² = 562 500
BC = √562 500 = 750 m
AC/AD = AB/AE = CB / DE
450/AD = 600/ 1 800
600 AD = 810 000
AD = 1 350
450/1 350 = 750/ DE
450 DE = 1 012 500
DE = 2 250
ABCDE = 600 + 750 + 900 + 2 250 = 4 500 m
