ABCD is a parallleogram and E is the mid-point of BC. DE and AB when produced meet at F. Then , AF =
2 AB
In || gm ABCD, E is the mid -point of BC. DE and AB are produced to meet at F.
∵E is mid point of BC∴BE=ECIn ΔBEF and ΔCEDBE=EC∠BEF=∠CED(Vertically opposite angle)and ∠EBF=∠ECD (Alternate angles)∴ΔBEF≅ΔCED (ASA criterian)∴DC=BFBut DC=AB∴AB=BFAF=AB+BF=AB+AB=2AB