二、填空题:13. [+2kπ, +2kπ](k∈z) .
14. 3
15. 1
16. b 三、解答题: 17.解:由题意可得解得,或 ∴α==或α==6. 18.解:(1)原式=sin(-4×360°+120°)cos(3×360°+30°)+cos(-3×360°+60°)sin(2×360°+30°) =sin 120°cos 30°+cos 60°sin 30° =×+× =1. (2)原式=cos+tan =cos +tan =+1 =. 19.解:列表: x
0
π
2π
-2cos x
-2
0
2
0
-2
-2cos x+3
1
3
5
3
1