Ph¬ng tr×nh lîng gi¸c
Bµi 1: Gi¶i c¸c ph¬ng tr×nh sau
2
2
2 2
x x
1. sin 2cos 2 0 6. 3sin3x-4cos3x=5
2 2
2. 30cos 3x-29sin3x-23=0 7. sin2x+( 3-2)cos2x=1
x
3. 9-4sin x-8cos 0
2
− + =
=
2 2
2 2
2
1
8. (sinx+cosx) = +cos x
2
4. cos2x+5sinx+2=0 9. cos x- 3sin2x=sin x+1
5. 3cot x-4cotx+ 3 0 10. 2sin3x-sin2x+ 3c
=
os2x=0
Bµi 2: Gi¶i c¸c ph¬ng tr×nh sau
2 2
1 1 10
1. 2( 3sinx-cosx)=3sin2x+ 7cos2x 11. sinx+ +cosx+ =
sinx cosx 3
2. 2sin x+sinxcosx-cos x+1=0 12. 1+tanx=2 2sinx
1

2 2
n x+cos x+ sin2x+cos2x=1+ 2
4. (tanx+7)tanx+(cotx+7)cotx+14=0 8. 4cos x +3tan x-4 3cosx+2 3tanx+4=0
Bµi 4: Gi¶i c¸c ph¬ng tr×nh sau
1.
4 4
4
sin 2 cos 2
cos 4
tan( / 4 ) tan( / 4 )
x x
x
x x
π π
+
=
− +
11. cos3x+cos2x-cosx-1=0.
2. sin2x+2cos2x=1+sinx-4cosx 12. cotx+sinx(1+tanx.tan
2
x
)=4.
3. sin3x + 2cos2x - 2= 0 13. tanx+tan2x=-sin3x.cos2x
4. 1+cosx+cos2x+cos3x=0 14. 9sinx+6cosx-3sin2x+cos2x=8
5. sin2x(cotx+tan2x)=4cos
2
x 15. 3(cotx-cosx)-5(tanx-sinx)=2
6. 1+cos
3
x - sin

1
sin
1
)
4
sin(22
+=+

19. 2tanx+cot2x=2sin2x+
x2sin
1

10.
0
sin22
cos.sin)sin(cos2
66
=

+
x
xxxx
. 20. sin
8
x + cos
8
x =2(sin
10
x+cos
10