Răspuns :
L = 20 cm
l = 20 : 2 - 2 = 10 - 2 = 8 cm
P = 2 × ( L + l ) = 2 × ( 20 + 8 ) = 2 × 28 = 56 cm
A = L × l = 20 × 8 = 160 cm ^2
L = 20 cm
l = 20 : 2 - 2 = 10 - 2 = 8 cm
P = 2 × ( L + l ) = 2 × ( 20 + 8 ) = 2 × 28 = 56 cm
A = L × l = 20 × 8 = 160 cm ^2