salut:)
ABCD-romb => AB=BC=CD=DA si AB || EF => AB=EF
P ABCD=P ABEF+P ECDF-EF=23+19-2AB
P=42-2AB !
AF || BE & AB || EF
=> ABEF-paralelogram
P₁=2(AF+AB)=23 cm
=> 2AB+2AF=23 (1)
FD || EC & FE || CD
=> ECDF-paralelogram
P₂=2(DC+FD)=19
=>2DC+2FD=19
=> 2AB+2(AB-AF)=19
2AB+2AB-2AF=19
=> 4AB-2AF=19 (2)
din (1) si (2)
=> 2AB+2AF=23 /(-2)
4AB-2AF=19
____________________
-4AB-4AF=-46
4AB-2AF=19
_______________+
-6AF=-27
=> AF=27/6=9/2
=> 4AB=19+2*9/2
=> AB=28/4=7 cm
=> P=42-2*7
P=42-14
P=28 cm
