∵△ABC、△ADE是等边三角形，∴AB=AC，AD=AE，∠BAC=∠DAE=∠B=∠ACB=60°，∴∠BAC+∠DAC=∠DAE+∠DAC，即∠BAD=∠CAE．在△BAD和△CAE中∵AB=AC∠BAD=∠CAEAD=AE，∴△BAD≌△CAE，∴BD=CE=15cm，∠ACE=∠B=60°...