Option Explicit
Sub EssaI()
Dim DerLig As Long, DerLig2 As Long
DerLig = Sheets("Origine").Range("A" & Rows.Count).End(xlUp).Row
DerLig2 = Sheets("Cumul").Range("A" & Rows.Count).End(xlUp).Row
Sheets("Origine").Range("A2:AA" & DerLig).Copy Destination:=Sheets("cumul").Range("A" & DerLig2 + 1)
End Sub