若BO,CO分别平分∠ABC和∠ACD,且∠A等于α,求∠BOC.

问题描述:

若BO,CO分别平分∠ABC和∠ACD,且∠A等于α,求∠BOC.

若BO,CO分别平分∠ABC和∠ACB,且∠A等于α,则有:
∠BOC
= 180°-(∠OBC+∠OCB)
= 180°-(1/2)(∠ABC+∠ACB)
= 180°-(1/2)(180°-∠A)
= 90°+α/2