∠AOB内有射线OC,OD,∠AOD=36度,∠COB=45度,且∠AOC=3/4∠DOB,求∠AOB的度数?

∠AOB内有射线OC,OD,∠AOD=36度,∠COB=45度,且∠AOC=3/4∠DOB,求∠AOB的度数?

∠AOC=∠AOD-∠DOC=3/4∠DOB
36°-∠DOC=3/4(-∠DOC+∠BOC)=3/4(-∠DOC+45°)
∠DOC=9°
∠AOB=45+36-9=72°