1( ) ( ) ( )⇔ − = + −1 2SIN COS 3 1 2SIN 1 SINPT X X X X( 2 )⇔ − = +...
1. ĐK:
1
(
)
(
) (
)
⇔ −
=
+
−
1 2sin
cos
3 1 2sin
1 sin
Pt
x
x
x
x
(
2
)
⇔
−
=
+
−
x
x
x
x
x
cos
2sin cos
3 1 sin
2sin
⇔
−
=
+
cos
3 sin
sin2
3 cos2
x
x
x
x
⇔
x
−
x
=
x
+
x
⇔
π
+
x
÷
=
x
−
π
÷
1
3
1
3
cos
sin
sin2
cos 2
cos
cos 2
2
2
2
2
3
6
⇔ + =
π
x
x
− +
π
k
π
hay
π
+ = − + +
x
x
π
k
π
2
2
2
2
3
6
3
6
= −
+
⇔ = −
x
π
k
π
(loại)
2
x
π
k
π
, k ∈ Z (nhận)
2
2
18
3
−
≥ ⇔ ≤
6 5
0