ΔABC≌ΔA'B'C',AD,A'D'分别是对应边BC和B'C'边上的中线.求证AD=A'D'∵ΔABC≌ΔA'B'C' ∴AB=A’B’ ,AC＝A'C'∴BD＝B'D' ∵在ΔADB和ΔA'D'B'中：AB=A’B’ ,AC＝A'C' BD＝B'D' AB=A’B’ ∴ΔADB≌ΔA'D'B'（SSS)...