wltf
幼苗
共回答了15个问题采纳率:100% 举报
1.
因为等边△ABC 且AF=DC,AB=AC,角BAC=角ACB
所以三角形ABF全等于三角形ADC
所以角DAC=角ABF
又因为角BED=角EBA+角EAB=角DAC+角EAB=角BAC=60度
2.(1)证明:∵DE = BA,∠DBE =∠BCA = 90º,又∠DEB+∠ABC = 90º,∠A+∠ABC = 90º,∴∠DEB =∠A,∴△ACB≌△EBD(AAS),则有BC = BD.
(2)由△ACB≌△EBD,得AC = EB
∵E为BC的中点,
∴EB =1/2BC.
∵BD = 8cm,BC = BD,
∴BC = 8cm.
∴AC = EB =1/2BC = 4cm.
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1年前
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