(1)① ∵∠A=40°∴∠ABC+∠ACB=180°-∠A=180°-40°=140°∵BO、CO分别为∠ABC和∠ACB的角平分线∴∠ABO=∠1,∠ACO=∠2又∵∠ABC+∠ACB=∠ABO+∠1+∠ACO+∠2∴∠1+∠2=(∠ABC+∠ACB)/2=70°∴∠BOC=180°-(∠1+∠2)=180°-70°=110° ② ∵∠A=60°∴∠ABC+∠ACB=180°-∠A=180°-60°=120°∵BO、CO分别为∠ABC和∠ACB的角平分线∴∠ABO=∠1,∠ACO=∠2又∵∠ABC+∠ACB=∠ABO+∠1+∠ACO+∠2∴∠1+∠2=(∠ABC+∠ACB)/2=60°∴∠BOC=180°-(∠1+∠2)=180°-60°=120° ③ ∵∠A=n∴∠ABC+∠ACB=180°-∠A=180°-n∵BO、CO分别为∠ABC和∠ACB的角平分线∴∠ABO=∠1,∠ACO=∠2又∵∠ABC+∠ACB=∠ABO+∠1+∠ACO+∠2∴∠1+∠2=(∠ABC+∠ACB)/2=(180°-n)/2∴∠BOC=180°-(∠1+∠2)=180°-(180°-n)/2=90+n/2 (2) ∵∠A=40°∴∠ABC+∠ACB=180°-∠A=180°-40°=140°∵∠CBD+∠BCE=180°-∠ABC+180°-∠ACB=360°-(∠ABC+∠ACB)=360°-140°=220°∵BO、CO分别为∠CBD和∠BCE的角平分线∴∠1+∠2=(∠CBD+∠BCE)/2=110°∴∠BOC=180°-(∠1+∠2)=180°-110°=70°