Bài tập: Giải phương trình lượng giác

Gi¶i c¸c ph¬ng tr×nh lîng gi¸c sau:

1 1 cos x sin x 0

2

 

    

sin x sin 2x sin 3x sin 4x

4



3 2sin2 x 1 2sin x2

4



  

sin x cos3x sin 3x cos x

8

6 sin8x cos6x  3 sin 6x cos8x  

7 3sin x 3 cos3x 1 4sin x  3

8 2sin x 1 cos 2x  sin 2x ,3

4 2 trªn  

9

2

4 3sin 2x

sin x cos x sin 3x 4



10 2cos4x cos 2x 4cos 2x 3cos 2x 3 

11 4cos x sin 30 0x cos 60  0 x cos 3x2

12 1 cos 2x 2 5

6cos x sin 2x



sin x 2cos 2x sin x cos 2x 4sin cos

2tg x 2tgx 1

cos x

  

16 tg5x tg3x

17 tg2xtg7x 1

18 2sin x cos x 1 cos x     sin x2

20 sin x cos x cos 4x4  4 

21 3sin x 2sin x cos x cos x 02   2 

22 tg3x tgx 0 

24 sin x sin 2x sin 3x sin 4x 22  2  2  2 

2cos x 1 sin 3 

26 sin x cos x 1 sin x cos x3  3  

29 cos x 2cos x 4sin x sin 2x2   

30 tgx tg2x tg3x 0  

32 cot g2x cot gx 8cos x  2

33 1 tgx 1 sin 2x      1 tgx

34 8cos x 3cos 4x cos 2x 42   

35 tg xtg 3xtg4x tg `x tg 3x tg4x2 2  2  2 

36

3 2

3

1 cos x

tg x

1 sin x







37

3x 3x

2 sin x 3







sin x cos x 32 sin x cos x  

sin x sin 3x sin x.sin 3x

4

40 cos 4xcos 2x sin x 2 5

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