Răspuns :
P=2L+2l= 2*4l + 2l =10l=40 cm, deci
l=40:10=4 cm
si
L=4l=4*4=16 cm.
Verificare: P= 2(L+l) = 2(16+4) = 2*20 = 40 cm, corect.
l=40:10=4 cm
si
L=4l=4*4=16 cm.
Verificare: P= 2(L+l) = 2(16+4) = 2*20 = 40 cm, corect.