函数y=cos^2(x+pi/2)的单调递增区间是?
问题描述：
函数y=cos^2(x+pi/2)的单调递增区间是?
答
kπ≤x≤kπ+π/2,k属于整数
cos^2(x+π/2)
=cos^2(x+π/2)-1/2+1/2
=1/2[cos(2x+π)]+1/2
π+2kπ≤2x+π≤2π+2kπ
解得kπ≤x≤kπ+π/2