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信息發(fā)布者:
?$ (1)$?證明:∵?$\triangle ABC≌\triangle DEF$?
∴?$∠B=∠DEF$?
∴?$AB// DE$?
?$ (2)$?解:∵?$\triangle ABC≌\triangle DEF$?
∴?$BC = EF$?
∴?$BE + EC=EC + CF,$?∴?$BE = CF$?
∵?$BF = 8,$??$EC = 2$?
∴?$BE+EC+CF=BF,$?即?$2BE+2=8$?
∴?$BE=3$?
∴?$BC=BE + EC=3 + 2=5$?
解:如圖所示
平移變換得到?$△A_{1}B_{1}C_{1}$?
對應(yīng)邊:?$AB$?與?$A_{1}B_{1},$??$AC$?與?$A_{1}C_{1},$?
?$BC$?與?$B_{1}C_{1}$?
對應(yīng)角:?$∠A$?與?$∠A_{1},$??$∠B$?與?$∠B_{1},$?
?$∠C$?與?$∠C_{1}$?
軸對稱變換得到?$△A_{2}B_{2}C_{2}$?
對應(yīng)邊:?$AB$?與?$A_{2}B_{2},$??$AC$?與?$A_{2}C_{2},$?
?$BC$?與?$B_{2}C_{2}$?
對應(yīng)角:?$∠A$?與?$∠A_{2},$??$∠B$?與?$∠B_{2},$?
?$∠C$?與?$∠C_{2}$?
旋轉(zhuǎn)變化得到?$△A_{3}B_{3}C_{3}$?
對應(yīng)邊:?$AB$?與?$A_{3}B_{3},$??$AC$?與?$A_{3}C_{3},$??$BC$?與?$B_{3}C_{3}$?
對應(yīng)角:?$∠A$?與?$∠A_{3},$??$∠B$?與?$∠B_{3},$??$∠C$?與?$∠C_{3}$?