苏科版八年级上册数学补充习题答案2017【汇编三篇】
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苏科版八年级上册数学补充习题答案2017(1)
探索三角形全等的条件(6)
1、连接BD.
∵ AB = CB, AD = CD,
BD = BD,
∴ △ABD ≌ △CBD(SSS).
∴ ∠A = ∠C.
2、∵AB = DC,AC = DB,BC = CB,
∴ △ABC ≌ △DCB(SSS).
∴ ∠ABC = ∠ DCB,∠ACB = ∠DBC.
∴ ∠ABC - ∠DBC = ∠DCB - ∠ACB,
即∠1 = ∠2.
3、△ABC ≌ △CDA( SSS),△ABE ≌ △CDF( SAS),
△ADF ≌ △CBE(SAS).证明略.
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苏科版八年级上册数学补充习题答案2017(2)
探索三角形全等的条件(4)
1、∵ AB ∥ CD,
∴ ∠ABE = ∠CDF.
∵ AE ⊥ BD,CF ⊥ BD,
∴ ∠AEB = ∠CFD = 90°.
在△ABE和△CDF中,
∵ ∠ABE = ∠CDF,∠AEB = ∠CFD,
AE = CF,
∴ △ABE ≌ △CDF(AAS).∴ AB = CD.
2、∵ △ABC ≌ △DCB,
∴ AB = DC,∠A = ∠D.在△AOB和△DOC中,
∵ ∠A = ∠D,∠AOB = ∠DOC,AB = DC,
∴ △AOB ≌ △DOC(AAS).
3、(1) 在△ABE和△ACD中,
∵ ∠A = ∠A,∠B = ∠C,AE = AD,
∴△ABE ≌ △ACD(AAS).
(2)∵△ABE ≌ △ACD,
∴ AB = AC,AB - AD = AC - AE,即DB = EC.在△BOD和△COE中,
∵ ∠DOB = ∠EOC,∠B = ∠C, DB = EC,
∴ △BOD ≌ △COE(AAS).
苏科版八年级上册数学补充习题答案2017(3)
探索三角形全等的条件(5)
1、∵ B是EC的中点,
∴ BE = BC.
∵ ∠ABE = ∠DBC,
∴∠ABE + ∠ABD = ∠DBC + ∠ABD,
即∠DBE = ∠ABC.在△DEB和△ACB中,
∵ ∠DBE = ∠ABC,∠D = ∠A,
BE = BC,
∴ △DEB ≌ △ACB( AAS).
∴DE = AC.
2、∵ CD ⊥ AB,EF ⊥ AB,
∴ ∠CDB = ∠EFA = 90°,
∵ AD = BF,
∴ AD + DF = BF + DF,即AF = BD.在△CBD和△EAF中,
∵ CD = EF, ∠CDB = ∠EFA,BD = AF,
∴△CBD ≌ △EAF(SAS).
∴∠A = ∠B.
3、∵ ∠AFB = ∠AEC,∠B = ∠C,AB = AC,
∴ △ABF ≌ △ACE(AAS).
∴ ∠BAF = ∠CAE.
∴ ∠BAF - ∠EAF = ∠CAE - ∠EAF,即∠BAE = ∠CAF.