Giải các phương trình lượng giác sau :
(2 sin x + 1)(3cos 4 x + 2sin x − 4) + 4 cos 2 x = 3
1.
sin 6 x + cos 6 x = 2(sin 8 x + cos8 x)
2.
cos x.cos 2 x.cos 4 x.cos8 x =
3.
π
8cos3 x + ÷ = cos 3x
3
4.
5.
6.
7.
8.
1
16
(2sin x − 1)(2sin 2 x + 1) = 3 − 4 cos 2 x
cos 2 x − cos8 x + cos 6 x = 1
sin 4 x − 4sin x + 4 cos x − cos 4 x = 1
3sin x + 2 cos x = 2 + 3 tan x
9.
10.
11.
12.
13.
14.
15.
2 cos3 x + cos 2 x + sin x = 0
2(tan x − sin x) + 3(cot x − cos x) + 5 = 0
4 cos x − 2 cos 2 x − cos 4 x = 1
sin x + sin 2 x + sin 3 x
= 3
cos x + cos 2 x + cos 3 x
π
sin x.sin 4 x = 2 cos − x ÷− 3 cos x.sin 4 x
6
x
x
π x
1 + sin sin x − cos sin 2 x = 2cos 2 − ÷
2
2
4 2
2 cos 2 x − sin 2 x = 2(sin x + cos x)
cos x − cos 2 x + cos 3 x =
16.
17.
18.
19.
20.
π
sin 3 x + ÷ = 2 sin x
4
1 + sin x + cos x + sin 2 x + cos 2 x = 0
tan x + tan 2 x + tan 3 x + cotx + cot 2 x + cot 3 x = 6
1 + sin 3 x = sin x + cos 2 x
sin 4 x + cos 4 x =
21.
1
2
7
π
π
cot x + ÷.cot − x ÷
8
3
6
22.
23.
24.
25.
26.
cos 2 2 x + 2(sin x + cos x)3 − 3sin 2 x − 3 = 0
4(sin 3 x − cos 2 x) = 5(sin x − 1)
sin x − 4sin 3 x + cos x = 0
cos10 x + 1 + cos8 x + 6 cos 3 x.cos x = cos x + 8cos x.cos 3 3 x
π 1
sin 4 x + cos 4 x + ÷ =
4 4
cos 3 x.cos 3 x + sin 3 x.sin 3 x =
27.
2
4