(1)∠AOB=84°,∠AOC与∠COB的度数之比是2:1
∠AOB=∠AOC+∠COB
则,∠AOC=1/3∠AOB=28°
(2)∠COB=2/3∠AOB=56°
DO是∠COB的平分线
所以∠BOD=1/2∠COB=28°