Răspuns :
P=90m
L=4•l=4l
inlocuim in ecuatie lungimea
4l+l=90
5l=90
l=90 supra 5
l=16
L=4•16=64
L=4•l=4l
inlocuim in ecuatie lungimea
4l+l=90
5l=90
l=90 supra 5
l=16
L=4•16=64