1、 1 1 2 km A B C CAB CBA B C _ km. ACB 2 BC BC 6 2 4 2 2 3 1. 3 1 2 A B 10 km B C 20 km ABC A C _ km. AC 2 100 400 700 AC 10 7(km) 10 7 3 ) ABCD AB CD ABC AB 2BC 2CD cos DAC _. CD a ACD CD 2 AD 2 AC 2 2AD AC DAC a 2 ( 2a) 2 ( 5a) 2 2a 5a DAC cos DAC 3 10 10 . 3 10 104 30 m _m. OM AOt 30(m) ON AO 3 3
2、10 3(m) MON 2 MN 900 300 3 3 2 300 10 3(m) 10 3 5. 24 km/h A S 15 min B S 7 B _km. AB 15 60 6 ABS BAS AB 6 ABS ASB BS AB BS AB 3 2(km) 3 2 1 A 40 30 B C A B B C _ ABC AB 20 CAB ACB BC AB BC 10 2( ) 10 2 2. d 0.6 km A B. AB 1 km 2 km/h A B 6 min _ km/h. AB v km/h sin 0.6 1 3 5 cos 4 5 1 10 v 2 1 10 2
3、 1 2 1 10 4 5 v 6 2. 6 2 3 CAB 1 000 S DSB BC _ 3 BAS ABS 15 ASB ABS 1 000 AB AB 1 000 2 BC AB 2 1 000. 1 000 ) P Q 300 3 P Q AB PAB PAQ PBA PBQ P Q _ AQ PB C QAB PAB PAQ PBA PBQ AQB ABQ AC CQ BC AQ. PQA PAQ PQA PQ AQ Rt ACB AC AB 300 3 3 2 450 PQ AQ 900. P Q 900 900 5. A 20 B 30 C _ / ACB B AC sin
4、B AB sin ACB AC AB B sin ACB 10 6 4 10 6 30 6 3 ( / ) 6 36 ) ABC A B C a b c a sin 2 (B C)0. cos A b 2 c 2 a 2 2bc 0 0 3 . A 3 2 . 3 27. AB C C B A C 10 D BDC AB _ BCD CD 10 BDC BCD DBC BC CD BC CD 10 2. Rt ABC AB BC AB BC 10 6( ) 10 6 8. ABC sin ABC 2 3 3 AB 2 D AC AD 2DC BD 4 3 3 cos C _. cos ABC
5、1 3 sin ABC 2 2 3 . 5 ABC BC a AC 3b 9b 2 a 2 4 4 3 a. ADB CDB cos ADB cos CDB 4b 2 16 3 4 16 3 3 b b 2 16 3 a 2 8 3 3 b 3b 2 a 2 6 a 3 b 1 AC 3 BC 3. ABC cos C BC 2 AC 2 AB 2 2BC AC 3 2 3 2 2 2 7 9 . 7 99 A 10 n mile C 9 n mile/h 21 n mile/h . 3 3 14 AC 10 ACB t h B AB 21t BC 9t ABC AB 2 AC 2 BC 2
6、2AC BC 21 2 t 2 10 2 81t 2 t 1 2 360t 2 90t 100 0 t 2 3 t 5 12 ( ) 2 3h. AB 14 BC 6. ABC BC sin CAB AB sin CAB 3 2 14 3 3 14 CAB CAB ) 6 2 3h 10 S A B O B 6 . S 3 (1) (2) 2 MN O S 3 (1) SC OB C CSB 6 ASB 3 . SA 3 Rt SAB BA 3 3 SC 3 CSO 6 Rt SCO OC 3. BC SA 3 OB 2 3 2 3 (2) SM SN SN a SM b. (1) SO 2
7、3 SOM SON cos SOM cos SON 3 2 1 b 2 3 3 2 1 a 2 3 a 2 b 2 26. MSN cos MSN a 2 b 2 2 2 2ab 11 ab 22 a 2 b 2 11 13 1 2 a b MSN (0 0 MSN 3 . S 1 10 000 m 50 m/s. 420 s _m ( 2 1.4 3 1.7) 7 CD AB D A DBC ACB AB 21 000(m) ABC BC sin A AB sin ACB BC 21 000 1 2 10 500( 6 2) CD AD CD BC DBC 10 500( 6 2 2 2 1
8、0 500( 3 1) 7 350. h 10 000 7 350 2 650(m) 2 650 2. 60 m AA1 BB1. AA1 BB1 BB1 AA1 2 C BB1 AA1 _ BB1 _m. BB1 AA1 AA1 60tan BB1 60tan 2 . C A1AC CBB1 AA1 30 30 BB1 AA1 BB1 900 3 600tan tan 2 900 tan 1 3 tan 2 3 4 BB1 60tan 2 45. 1 345 3. M N A B A B AM 100 BN 200 M P A 100 3 Q Q B BQA tan 2 A B Rt AMP APM AM 100 8 PM 100 3 QM PQM QPM PQ 100 3 PQM QM 100 3. Rt AMQ AQ 2 AM 2 QM 2 AQ 200. Rt BNQ tan 2 BN 200 BQ 100 5 cos 5 5 . BQA BA 2 BQ 2 AQ 2 2BQ AQcos (100 5) 2 BA 100 5. A B 100 5
