BC=72-18-24=72-42=30
'Se onbserva ca "
18²+24²=30² deci, Rec Teo Pitagora tr e dr in A dar nu aplicam nimic de aici
AD=6⇔DE=18-6=12
ED=16⇒AE=24-16=8
cum AD/AB=6/18=1/3 si AE/AC=8/24=1/3⇒DECB trapez cu DE||BC
si (T.F.A.) DE/BC=AD/AB=1/3⇒DE=30/3=10cm
Atunci perim BCED=12+10+16+30=42+26=68cm
as simple as that!!!