Repede te rog dau coroana

p = 60 cm
l = L : 2, L = 2 x l
P = 2 x L + 2 x l
60 = 2 x 2xl + 2 x l
60 = 4l + 2l
60 = 6 l
l = 60:6, l = 10cm
L = 10 x 2, L = 20 cm