题目
已知:直线AB与直线CD交于点O,过点O作OE⊥AB. (1) 如图1,∠BOC=2∠AOC,求∠COE的度数; (2) 如图2.在(1)的条件下,过点O作OF⊥CD,经过点O画直线MN,满足射线OM平分∠BOD,在不添加任何辅助线的情况下,请直接写出与2∠EOF度数相等的角. 答案:如图1,∵∠AOC+∠BOC=180 ° ,且∠BOC=2∠AOC,∴∠AOC=60 ° , ∵OE⊥AB, ∴∠AOE=90 ° , ∴∠COE=90 ° ﹣60 ° =30 ° ;
如图2,由(1)知:∠AOC=60 ° ,∵射线OM平分∠BOD, ∴∠BOM=∠DOM=∠AON=∠CON=30 ° , ∵OE⊥AB,OC⊥OF, ∴∠AOE=∠COF=90 ° , ∴∠AOC=∠EOF=60 ° , ∴∠AOD=∠BOC=∠
40.It is important that she___________with
Mr Williams immediately.
41.
A.speak
B.spoke
C.will speak
D.to speak