∵AO⊥BO
∴∠AOB=90°
∵OD平分∠AOC
∴∠AOD=∠DOC
∵∠BOC=3∠AOD
又∴∠AOD+∠DOC+∠BOC=360°-90°=270°
即5∠DOC=270°
∴∠DOC=270°÷5=54°