1、2021 上海 16 區(qū)中考數(shù)學(xué)二模難點(diǎn)匯編 舉一反三刺練難點(diǎn)專題一 新定義（填空題 17 或 崇明普陀楊浦青浦靜安閔行松江黃埔寶山虹口嘉定浦東新區(qū)金山長寧奉賢松江【 年【 年 18 n n n 2 3 2n 180 n 2n+3n=180 n=30 2n 6n =n+2n+6n=180 n=20 6n n+3n+6n=180 n=183 n 23n+3n+ n =1802112n 180n 36011 20 183601118 1 n n 2 3 6x 3 2 1 x x+3x+6x+6x=36016x=360 x=22.5 【2021 年寶山區(qū)】17. (2B(3 2 “” y 10 x

2、2 “ ” x y 10 x“” aba aab3 AB( )2b 23 a3 b 5B2 52B5A BAC=90 A x B C y 10 x CD x D _. CAD ACD ADC ACD ACABOCAD(AAS) AD OA B(0,3) OB AD C 10 y x10 310C ( 310( 3y 10 x【 年18 “” BC mABC ” m m 2ABC mABC BC 2 A M A ADBC D ABC4BC AD 4 3 A MN m 2 4 4 【2021 年虹口二模】17“ “” BD ”ABCBAD 1775 1. 1 ABCD ADBAD=120C=75B

3、D BD ABCD 1216 1 BAC AC D A ABCD BCD .ADB= BAD=120 ABD=ADB .BCD DBC=30BCD AC ABCD ACD .AB=AD=BC AD=AC ADCABC BCD=60+75=135. AD=CD ABCD AC=CD C BFCE CE 12AD ACE= ABFE . BF=AE.AB=AD=BC BF 12BC BCF=30.BAC.CEBAC=ACE1 ACE 2 BCD 【舉一反三 2 ._A.B.C.D. ABD BAD=90. ABCD ABC . ACD ABD AB=AD=BC AD=AC ABC ABC=60.

4、AD=CD ABCD AC=CD C CE E AB=AD=BC AD=AC ABC ABC=60. AD=CD ABCD AC=CD C CE 12AD ACE=BAD=AEF=BFE=90 ABFE . BF=AE.AB=AD=BC BF 12BCBCF=30.BAC.CEACE1 BAC 2ABC 60150.2 AC ABCD ACD 1 2 . 【 年【 年17. A 60 E AD E _ 2 7 A E AGBC G H AGHE AB=6 =60 BG=3 EH =-HC-1=1 EF A AGEH H ABCD AB60 3 3 EH BGGH-21 AE2HC2-1 Rt

5、EFH EF 2 FH 73 1. D BC D ABC E _. AGBC G EFAG.AB=AC=5 12BC . Rt DC DC . eq oac(,S)2 eq oac(,S)1 1BC 2 1 2 EFAGCEF AG EC 154 AE 15 .4 54【202117. a a2+b2c2“ac abc2561a+1n +_ n42+4 ”abcac=”c b+1 n+1nc2b2=n+12+12-2=2+1 =2n+2 n+2+n+4n2+4+1” =+1 1 bc a (a, b, c) . 1000 “ (3,4,5) aaa b c ( ) (a, . 5 25 12

6、25 (5,12,13) 7 49 24 25 49 (7,24,25) . 11 2n+1 n 1 .(11,60,61) .1 n .3 ) n )(2 n n )2(2 n) .5 n n n (2 n n n .6 (8,15,17) .8 2a( a, c) 10003,4,5).a( a b , d ) d=13_.533 13( 6.【2021 2 217. A _2 B A B yx 24 42 AB 2 2 2 1 B A B _y k B ( x, )x y kx A(2,4) k 2 x 8( x, )x| 2 4 20 x | AO | 20 64x 20 64tt t 20t t 4 x 4 2 y ( ( (2 2)2 2 5 4)2 2)2 4 8 (2 2(4 2 【2021【2