∠AOB=∠AOC+∠COB=3∠AOC∠AOD=∠AOB/2=(3/2)*∠AOC∠AOD=∠COD+∠AOC(3/2)*∠AOC=∠COD+∠AOC∠AOC/2=∠COD∠AOC=2∠COD=36°∠AOD=∠AOC+∠COD=54°∠AOB=2∠AOD=108°
图！
