15题,谢

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15题,谢15题,谢 15题,谢∵∠A=α,∴∠ABC+∠ACB=180°-α,∵BO、CO分别是∠ABC与∠ACB的角平分线,∴∠OeC+∠OCe=1/2∠ABC+1/7∠ACB=1/2(

15题,谢
15题,谢
 

15题,谢
∵∠A=α,
∴∠ABC+∠ACB=180°-α,
∵BO、CO分别是∠ABC与∠ACB的角平分线,
∴∠OeC+∠OCe=1/2∠ABC+1/7 ∠ACB
=1/2 (∠ABC+∠ACB)
=1/2(180°-α)
=90°-1/2α,
∴∠BOC=180°-(∠OBC+∠OCB)=90°+1/2α.