八上数学期末专题训练三角形全等的判定

2024-01-03
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简介:
【一】已知:△ABC是等边三角形,∠GAB=∠HBC=∠DCA,∠GBA=∠HCB=∠DAC。求证:△ABG≌△BCH≌△CAD。解:∵△ABC是等边三角形∴AB=BC=CA在△ABG与△BCH中∠GBA=∠HCB,AB=BC,∠GBA=∠HCB∴△ABG≌△BCH(ASA)同理可证:△BCH≌△CAD∴△ABG≌△BCH≌△CAD【二】已知:如图∠1=∠2,∠3=∠4,求证:△ABC≌△ABD。解:∵∠ABC与∠3互补,∠ABD与∠4互补,又∵∠3=∠4,∴∠ABC=∠ABD在△ABC与△ABD中∠1=∠2,AB=AB,∠ABC=∠ABD∴△ABC≌△ABD(ASA)【三】已知:AB=CD,AB∥DC求证:△ABC≌△CDA解:∵AB∥CD∴∠1=∠2在△ABC与△CDA中AB=CD,∠1=∠2,AC=CA∴△ABC≌△CDA(SAS)