1、 2018 1 ( ). (A) 50 (B) 100 C) 50 (D) 2 C 90 cos A= 4 5 A 3 5B 5 4C 3 4D 4 33 3 tanA-3 2 + 2cosB- 3 =0 ABC A B C 60 D 4. . ABCD E AD A ABE CDE BCE C ABE DEC B ABE CDE BCE D ABE EBC 5 . ABC 2, 6 ,2, A B C 1 3, ABC A B C , A B C ( ) A. 2 B. 2 2C. 2 6D. 3 3 4 7 8 10 6 ABC C B A C B BC B A AB C A AC C B
2、 BC A A C C ABC C B A A 1 B 2 C 3 D 4 7 ABC DE BC AD 3 BD 2 ADE DBCE A 3:2 B 3:5 C 9:16 D 9:4 8 ABCD M N AC ME AD NF AB. NF = NM = 2 ME = 3 AN = A 3 B 4 C 5 D 6 9 Rt ABC AB AC M CM MB A. 2: 3 B. 3:2 C. 3:1 D. 1: 3 10 AB D 1 CD A 3 100 F A AB A 50 3B 51 C 50 3 1 D 101 11 ABC BAC=90 AB=AC D AC DE BC E
3、 BD tan DBC A 1 3B 21 C 23 D 1 4 11 12 13 14 12 Rt ABC ACB=90 A=30 BC=2. ABC C n EDC D AB DE AC F n A. 30 2 B. 60 2 C. 60 2 3D. 60 3 13 ABC AC AB E D AB AC AD AC 3 AE AB 3 , F BC : FDB ADE . 14 ABC AB=5 AC=3 D AB ACD= B AD 15 A B BC 30m AC m 16 2 3 17 EFGH ABC FG BC BC=3 AD=2 EF= EH EH 15 16 17 18 1
4、8 CD EF A D B F BF D A B 2 CE=3 A B C E EF= 4 19 O 256 OABC OA1B1C1 OA1 OA 1 2 OA2B2C2 OA2 OA1 1 2 OA3B3C3 OA3 OA2 1 2 n OAnBnCn OABC n= 20 21 22 20 . F A D E B C 21 ABCD E CD BE AD F CD DE 2 1 ABF CEB 4 DEF 2 ABCD 22 CD . 2.5 . 1.5 A D 60 B E 30 14 AB . 0.1 3 1.73 . 23 ABC BC 18 AD 6 D BC AD BC 1 s
5、inB 2 DE EF E AB BE=2AE EF BC F DE 23 24 24. A B D BAC 60 DAE 45 D m 2 3 DE B BC 25 Rt ABC AC=6cm BC=8cm M B BA 3cm A N C CB 2cm B t 0 t MN 1 BMN ABC t 2 AN CM AN CM t 3 36 1 2 3 4 5 6 7 8 9 10 11 12 A D A B A C C B B C A C 3 21 13. A= BDF 14. 1.8 15. 10 3 16. 4 9 17. 1.5 18. 5.7 19. 16 20 B= ACD ADC= BCD, ADC CDB,CD:BD=AD:CD 21 1 ABCD A= C AB CD ABF= CEB ABF CEB 2 ABCD AD BC AB CD DEF CEB DEF ABF 22 23 1 Rt ABD BD=DC=9 AD=6 AB= = =3 sinB= = = 2 EF AD BE=2AE = = = = = EF=4 BF=6 DF=3 Rt DEF DE= = =5 24 25
