a)m∡DAB=60°⇒m∡DBA=30°⇒(teorema unghiuluide 30° in tr dr ADB)⇒AB=12⇒Perim =2(AD+AB)=2(6+12)=2*18=36
b)AE=SF=12:2=6
AE||DF din cele 2 de mai sus⇒AEFD patrulater cu 2 laturi opuse || si ≡, AEFD paralelogran
AD=AE=6cm⇒AEFD paraslelogram cu 2 laturi consecutive confruente,AEFDromb
Perimetru AEFD=4*6=24
c)fie AC∩BD={O}
intr-un paralelogram diagonalelse injumatatesc⇒DO≡OB
AE≡EB,
EF|| AD⇒EO l.m in ΔDAB⇔EO∩DB={O}
