Răspuns :
L=20 cm
[tex] \frac{l}{L} = \frac{4}{5} ; \frac{l}{20} = \frac{4}{5} ; l= \frac{4*20}{5} =16 cm[/tex]
perimetrul=2*16+2*20=32+40=72 cm
[tex] \frac{l}{L} = \frac{4}{5} ; \frac{l}{20} = \frac{4}{5} ; l= \frac{4*20}{5} =16 cm[/tex]
perimetrul=2*16+2*20=32+40=72 cm