摘要：如图5-3-12.AB∥CD∥EF,那么∠BAC+∠ACE+∠CEF等于( ) 图5-3-12 A.180° B.270° C.360° D.540° 解析:∠ACE=∠ACD+∠DCE.根据两直线平行.同旁内角互补.有∠BAC+∠ACD=∠DCE+∠CEF=180°.∠BAC+∠ACE+∠CEF=360°． 答案:C

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