高一三角函数题,高手来解

1,
2cosx-1>=0
cosx>=1/2
画出单位圆可知
x∈[2kπ-π/3,2kπ+π/3],k∈Z
2,
3-4sin²α>0
sin²α<3/4
|sinα|<√3/2
解得α∈(2kπ-4π/3,2kπ+π/3),k∈Z

(1) 2cox-1>=0
-π/3+2kπ=<x<=π/3+2kπ
(2)-π/3+2kπ <x<π/3+2kπ 或2π/3+2kπ <x<4π/3+2kπ

2COSx-1>0
cosx>1/2
2k∏-∏/3<=x<=2k∏+∏/3
(2)k∏-∏/3<=x<=k∏+∏/3