O是三角形ABC内一点,且OB、OC分别平分角ABC和角ACB。(1)若角A等于46度,求角BOC
O是三角形ABC内一点,且OB、OC分别平分角ABC和角ACB。(1)若角A等于46度,求角BOC
日期:2013-09-05 20:06:16 人气:2
1、解:
∵∠A=46
∴∠ABC+∠ACB=180-∠A=134
∵BD平分∠ABC
∴∠ABD=∠ABC/2
∴∠BEC=∠A+∠ABD=∠A+∠ABC/2
∵CD平分∠ACB
∴∠ACD=∠ACB/2
∴∠BOC=∠BEC+∠ACD
=∠A+(∠ABC+∠ACB)/2
=46+134/2
=113°