求y=1-cos(x/2)的递增区间

题目

求y=1-cos(x/2)的递增区间
答案[4kπ,4kπ+2] 求详解.

答案

y=1-cos(x/2)
=1-sin(π/2-x/2)
=1+sin(x/2-π/2)
2kπ-π/2