$4.(2)解:设∠ABE=x°$
$则∠CBE=2∠ABE=2x°\ $
$∵AB=AC$
$∴∠ACB=∠ABC=3x°\ $
$∵∠ACB=2∠ACD=3x°$
$∴∠ACD=1.5x°$
$∵△CAD≌△ABE\ $
$∴∠BAC=∠ACD=1.5x°$
$∠ADC=∠AEB$
$∵∠ABC+∠ACB+∠BAC=180°$
$即3x+3x+1.5x=180,解得x=24\ $
$∴∠ABE=24° $
$∴∠BAC=36°\ $
$∴∠ADC=∠AEB=180°-24°-36°$
$=120°$