（1）图中与∠COE互补的角是∠DOE ∠BOF(2)∵OE⊥AB， OF⊥CD∴∠AOE=∠COF=90°∴∠EOF=∠AOE+∠COF-∠AOC=180°-∠AOC∵∠AOC= 1/5∠EOF∴∠AOC= 1/5(180°-∠AOC)∴∠AOC=30°
