延长BD,与AC交于点E
∵∠BAD = ∠EAD
AD = AD
∠ADB = ∠ADE = 90°
∴ △ADB≌△ADE
∴ AE = AB = 12
BD = DE
∵BM = CM
∴ DM = 1/2 EC
∴ EC = 2DM = 10
故:AC = AE+CE = 22
延长BD,与AC交于点E
∵∠BAD = ∠EAD
AD = AD
∠ADB = ∠ADE = 90°
∴ △ADB≌△ADE
∴ AE = AB = 12
BD = DE
∵BM = CM
∴ DM = 1/2 EC
∴ EC = 2DM = 10
故:AC = AE+CE = 22