Răspuns:
Explicație pas cu pas:
MN=linie mijlocie=(AB+DC)/2
a)MN=(4+10)/2=14/2= 7cm
b)AB=2MN-DC AB=2×7-12=14-12=2 cm
c)DC=2MN-AB DC=2×8-10=16-10=6 cm
d)DC+AB=2MN DC+AB=24
AB=DC/2 DC+DC/2=24 3DC=48 DC=16 cm AB=16:2=8 cm
3.Se duce BF⊥DC ⇒triunghiul dreptunghic isoscel BEC ∡ C=45°⇒
BE=AD=AB=EC=8 cm
Baza mare DC=DE+EC=8+8=16 cm
MN=(DC+AB)/2=916+80/2=24/2=12 cm
