如图,AC=CE,DE=AB,且DC<BC,求证∠B+∠D=180

2025-06-28 16:27:09
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回答1:

延长BD至F,使CF=BC.连接EF.
∵AC=CE,BC=CF
∴AB//EF,EF=AB=DE.
∴∠B=∠F=∠EDF
∵∠EDF+∠CDE﹙∠D﹚=180°
∴∠B+∠D=180°