ex 7 si 8 repede ...

Răspuns:
7) P=2(L+l)
P=12dm
AB=L=4dm
AD=l=?
12=2(4+l)
12:2-4=l=>AD=2dm
______________
8) P=24cm
AB=2CD=>L=2l=>L=2·4=>AB=8cm
24=2(2l+l)
24:2=3l=>l=12:3=>CD=4cm