八年級上數學補充習題答案
每道錯的八年級數學補充習題做三遍。第一遍:講評時;第二遍:一週後;第三遍:考試前。小編整理了關於,希望對大家有幫助!
***一***
探索三角形全等的條件***7***
1、***1*** 圖略;
***2*** 在△OPE和△OPF中,
∵ ∠EOP = ∠FOP,OP = OP,
∠OPE = ∠OPF= 90°,
△OPE ≌△OPF***ASA***.
∴ PE = PF.
2、***1*** 圖略;
***2*** 在△OPM和△OPN中,
∵ ∠MOP = ∠NOP,∠PMO =
∠PNO = 90°,OP = OP,
∴ △OPM ≌ △OPN***AAS***.
∴ PM = PN.
***二***
探索三角形全等的條件***8***
1、∵ AB ⊥ BD, CD ⊥ DB,
∴ ∠ABD = ∠CDB = 90°,在Rt△ABD和
Rt△CDB中,
∵ AD = CB, DB = BD,
∴ Rt△ABD ≌ Rt△CDB*** HL***.
∴ AB = CD.
2、在Rt△ABF和Rt△DCE中,∠B = ∠C
= 90°,AF = DE,AB = DC,
∴ Rt△ABF ≌ Rt△DCE*** HL***.
∴ BF = CE.
∴ BF - EF = CE - EF,即BE = CF.
3、在Rt△ADE和Rt△ADF中,
∵ ∠AED = ∠AFD = 90°,DE = DF,AD = AD,
∴ Rt△ADE ≌ Rt△ADF*** HL***.
∴ ∠EAD = ∠FAD.在△ADB和△ADC中,∠ADB = ∠ADC = 90°,AD = AD,
∠BAD = ∠CAD,
∴ △ADB ≌△ADC***ASA***.
∴ AB = AC.
4、在Rt△ADB和Rt△BCA中,
∵ ∠ADB = ∠BCA = 90°.BD = AC, AB = BA,
∴ Rt△ADB ≌ Rt△BCA***HL***.
∴ AD = BC.在△ADC和BCD中,
∵ AC = BD,AD = BC,DC = CD.
∴△ADC ≌ △BCD.
∴ ∠2 = ∠1.
***三***
全等圖形