Răspuns :

Răspuns:L = 3l

L + l = 3l + l = 4l

P = 2 x (L + l)

L + l = P : 2 = 800 cm : 2 = 400 cm

4l = 400 cm

l = 400 cm : 4 = 100 cm

L = 3 x 100 = 300 cm

P patrat = 4 x 300 cm = 1200 cm