2020-2021学年八年级数学上册尖子生同步培优题典 专题1

2222222222222222222222222222222222222专题一定是直角三形吗姓名：__________________注意事项：

班级：______________

得分：_________________本试卷满分100分，试题共24题．卷前，考生务必用0.5毫米黑色签字笔将自己的姓名、班级信息填写在试卷规定的位置．一、选择题（本大题共小题每小题3分，共30分）在每小题所给出的四个选项中，只有一是符合题目要求的．1A48B892425D512aba+bc+48B+89C7+2425D5+11122ABCACAB23

BABBCACDBC23+45ABCBBCACAB+ABCCAB23ACx23xx+318030AC306090ABCD1ABCD1

22222222222222222222222222222222222222223D13CD5A14B13C12D9ADCADCADBCABDBD1213CD5AC169AD+CD144+25169CDACADCADC90ADB9015AD12BD

2

2

2

9BDCD144A34511C345

B13512111D34522+45B+121311C+≠，4531D452225AB10AC86AC2

22222222244222222222244222222DBDCD5A14

7C4

25D4ABCADDBABCAB86

BCABCDBCDxADDBxCDBCD+BCDB+68，7x7CD6ABCBCaAABCBAB13ABCCc916ABCDacABCA90ACABC180A90ABCBABC13+BCA90ABC3

222222222222222222222222222222222222222222222222222222222222Cc916+bABCDacABCB90D71AABCABDCACDDBCD5BC2CD310DA+420AC310A+10ACABCB+25BDABDCACCD20ADACDDCD+BC1525BCDD8ABCAabcCc123

BA13DAacb

+caABCBC123+BC1804

36222222362222225222222222222C18090ABCCab2abcABCDCABC+BAA++C180A90ABC9ABCabcABCABCA45Cabc

Bbc725DCBABAB34C18075ABCB725ABCCabcbc+aABCDBABC18090ABC10ABCAacbBAB45Cb45Dab1213kk5

222222222222222222222222bca+bcbABCBC345C90ABCCa3b4cABCDa5b1213a+c二填题本题8小题每题3分共24分请答案接写横上DCE45BCAG90CGAACBDCECAGCGAGAGCG1+25AC1+310AG+CGACCGA90CAGCAG45CAFBCAAFGCDEAFGCDE6

22222222222222222222222222222222222222DCEACBDCECAFCAG45125842+bc0.6+0.85+12138+15174+5213ABCcmcmABC30ABCABCcm12cm13cm5+1213ABC12cm1ABCcm12cm30230cm

14ac+bcabcbca

bcac7

211阴影222222222222222211211阴影222222222222222211122222222222222222215ADCAD8CD6BCm26mACACBSADCDADCCD6mAD8ADC90BC26ACADCD8+6ABCAC+BC10676AB26ACBCACBACBSACADCD8696阴影

m

216a+bcn+2a2+1babc2nnn2+1a2+1b2nnn17

3524

72

5

60618

222222222225222222222225321+121+2121+21+122+122+2132+22+123+123+2253+23+124+124+2414+24+160561

+25186cmABBCcm/s1PQtst

3122

sPBQBQBQPBPQABC6AC60PQB90302BQ62BQ62x2x3QPB90302PBx22x12312BPQ259

222222222222222221△eq\o\ac(△,S)eq\o\ac(△,)2231225三解题本题6小题共46分解时写出字明证过或算骤19AB43DC12ADACABCACDABC4BCB905ACD12ADDC+1213169DC+ADACDS5342420ABCDABADADCD13BC1210

12△2222222112△222222212△222BDBDBDCABCDBD4AB3cmBD

2

2

2

255SABBDC+1213BD+BCCDBDCDBC90S30S

S3024cm四边形△eq\o\ac(△,S)ABCD2421ABCDAD24ABC90ACACADCeq\o\ac(△,Rt)AC+CAC11

2222222222882222222222222882222222422222222222ABC90eq\o\ac(△,Rt)ABC

2

2

AC=25cmAD

+DC25ACADCD90DAB++BCDD180DAB+BCD180A+18022ABCabcan1b2nn+112b2ABC3bcqab24n23𝑎2𝜋3ABCabn1b+11abn1+2nnn+1，cn+1abcCABC1𝑏2b222424n212

11221𝑎122282222𝑐122𝑐2𝜋𝜋𝑎𝑏22288882211221𝑎122282222𝑐122𝑐2𝜋𝜋𝑎𝑏22288882222222111122222a3ABC3463bp

𝑎2𝑏q22

𝑏8

ABCabcc2

a+bp+2313cmDC12AB3cmBC4cmABCDACABCACD

5cmABC25AC525ABCABCDCD3536cm

2434535512137242513

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