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