1、解三角形周長問題專 A B b c sin sin sin A sin 1 B 2 b B A C sin A sin b ac a 2 2 1 B B B b 2 B cos ) (a ) 3) (a ) 4 a 3 ac 1 1 3 ac sin 2 2 ABC b 1 2 2 2sin C b2 5c2 bc 4 9 7 1 3 3 c 2 4 2 c B C 2sin B C 1 1 2 C B sin B C cos C 1 ) 3 3 cab cos c 2c c 4 2 53 c c 4 2 5 5 b 3 4 2 5 5 b 3 2 5 2 2 2 A a b 5 1 sin(

2、 )sin( ) 1 A 的2 a 1 )sin( ) (3 3 1 1 A A)( A cos ) sin A A sin cos A 2 2 4 4 4 4 3 1 1 1 2 (1cos2 ) (1cos2 A sin 2 A A 4 8 8 4 sin(2 1) 2 5 ) 6 6 32 b sin A sin B sin C 2 2 3 B 3 C a 2 2 2 (sin B sin C ) B sin( ? ) B ) 3 3 6 0 B 2sin( ) (1 3 60 3 ABC B a b c S 2S AB 1 A 2 a 7 D BC 2 b A b A sin A 3

3、A tan (0, 2 ABC abc A a b A c 2 2114 B B 5 714 Rt ABcos B BD 4 21 AD BD B 5 ABD 2 7 10 7 5 14 f ( sin( x x ) sin( ) 2cos 6 x R 1 f ( x) 2 ABC a b B C a f A 3 f ( ) 3 x x cos 2cos 3sin cos 2sin( ) 2 6 2sin( ) ( x) 2sin( x ) f ( x) 1 f ( ) 12 f A ) ) 20 A 6 ABC 3 1 bc sin bc 3 2 3 bc ) ) (b ) ABC B a

4、b c ( 3 A (1 cos C B 9 34 A 4 a 2c b _ ABC 3 sin A (1 C ) sin C cos( A ) C ( B B ) sin C 1 C (0, C B ) B ) 6 0 6 6 6 9 ac sin ac 4 a 1 a ) 2 36 a 2ac 2 a A ABC c sin 3 2 a 3sin 6 c 3sin( ) 4 3 a 6 3 2 6 6 2 a c cos a 1 2ac 2 c 3 ABCD BC 7 1 7142 BCD cos CBD 714 sin CBD 1 CBD 1 7 3 21) 14 14 BCsin sin BDC sin BDC BC CBD BDC BDC 2 BCD CBD BCBD CD 2 7 72 7 3 BD BD x AD B