1、七年级上学期期中考试数学试题及答案七(上)数学期中考试 考试时间120分钟,满分120分 哈工大附中七(上)数学期中考试答案 2020.11.04一、选择题(每小题3分,共30分)12345678910BCDABDDBCA(5对)二、填空题11. 3 ;12. -3 ;13. 720 ;14. 54 ;15. 3 ;16. 5 ;17. 80 ;18. 240 ;19. 72或108 ;20. 10 ;三、解答题(21题8分,22题6分,23、24题8分,25、26、27题10分,共 60分)21.(1)x = 8 (2)x = 8 22.(1)(2)如图 (3)323. a = 24. 证明
2、:ADEBCF=180, ADEADF=180 ADF =BCF(同角的补角相等) ADBC(同位角相等,两直线平行) BE平分ABCABC = 2ABE(角平分线定义) 又ABC = 2E ABE = E ABEF(内错角相等,两直线平行) ADBC BADABC = 180(两直线平行,同旁内角互补) BE平分 ABC,AE平分 BAD ABE = ABC,BAF = BAD ABEBAF = ABCBAD =180 = 90 ABEF(己知) BAF = F(两直线平行,内错角相等) ABE = E E F = 90(等量代换)25.(1)略(2)58。解略26.解:(1)第一次购买了4
3、00千克,第二次购买了800千克(2)设该水果店水果每千克售价a元400(13%)a800(15%)a600 = 56003558 a = 8.5答:该水果店水果每千克应定价8.5元。27.(1)证明:ABCD,AHE =HED AHE =GEF,GEF =HED GEF =GEHHEF,HED =FEDHEFGEH =FED 又 EG HE,GEH = 90,FED = 90, EF CD(2)过点F作FSAB,FHB =HFS FMHF,HFM= 90,HFSSFM = 90 ABCD, FNCD, EF CD, EFFS SFE= 90,SFMMFE = 90 HFSSFM =SFMMF
4、E HFS=MFE,FHB =MFE (3)过F作OFAB交HN于O BHF=HFO,BHRRHF =HFO HR平分BHF,设BHR =RHF = , HFO =BHRRHF = = 2, FHB =MFE,MFE =FHRBHR =BHF = 2, MFE =MFHMFE = 902, FT平分HFE,HFT =EFT =HFE = 45, OFT =HFTHFO = 452 = 45, ABCD且ABOF, CDOF, OFT =FTE = 45,过R作RSAB, HRS =BHR = ,ABRS且ABCD, RSCD, SRT =RTD = 45,HRT = 45 = 45, HRNHRK = 180,HRNHRNNRK= 180 NRK = 1804545 = 90,HNRK,HNK =NRK = 90 在HRT中 SHRT = SHRF SRFK =(HNRK) SHRK = 9,HNRK= 9,9 = 9, RF = 2 答:RF的长是2。