(60 m ; 120 m)
A = l×w = 7200m²
P = 2w + 2l = 360m
lw = 7200 => l = 7200/w
2(w + l) = 360 => w + l = 180
w + 7200/w = 180
w² + 7200 - 180w = 0
w² - 60w - 120w + 7200 = 0
w(w - 60) - 120(w - 60) = 0
(w - 60)(w - 120) = 0
w₁ = 60m => l₁ = 7200/60 = 120 m
w₂ = 120m => l₂= 60 m