Răspuns :
Răspuns:
P=2(L+l)
l=L/3=>L=3l
80=2(3l+l)
80:2=4l
l=40:4=>l=10cm latimea
L=3×10=>L=30 cm lungimea
Răspuns:
P drep=80cm
L |.........|..........|..........|
L |.........|..........|..........|
l |.........|
l |.........|
1)aflam latimea dreptunghiului:
80:8=10 cm
1)aflam lungimea dreptunghiului:
10×3=30cm
v:2×(l×L)=2×(10+30)=2×40=80cm
corect
Coroana!!