在AC上截取CM=CD
∠B=60°
∠FAC+∠FCA=60°
∠AFC=120°
∠DFC=60°
△CDF≌△CMF
∠DFc=∠MFC =60°
∠AFM=60°
∠AFM=∠EFA=60°
△AEF≌△AMF
AE=AM
AC=AM+MC=AE+CD
在AC上截取CM=CD
∠B=60°
∠FAC+∠FCA=60°
∠AFC=120°
∠DFC=60°
△CDF≌△CMF
∠DFc=∠MFC =60°
∠AFM=60°
∠AFM=∠EFA=60°
△AEF≌△AMF
AE=AM
AC=AM+MC=AE+CD