a) \(∆BCA = ∆ MND;\; \)
\(∆ ACB = ∆DNM;\)
\(∆ BAC = ∆ MDN\).
b) Vì \(∆ABC = ∆ DMN\) nên \(AB = DM; AC = DN; BC = MN\)
Mà \(AB = 3cm, \,AC = 4cm,\, MN = 6cm\)
Suy ra: \(DM = 3cm,\, DN = 4cm,\, BC = 6cm\)
Chu vi \(∆ABC\) là: \(AB + AC + BC = 3 + 4 + 6 \)\(\,= 13\, (cm)\)
Chu vi \(∆DMN\) là: \(DM + DN + MN = 3 + 4 + 6 \)\(\,= 13 \,(cm)\).
