y=√sinx+√cos-1/2
sinx≥0
x∈[2kπ,2kπ+π]
cosx-1/2≥0
cosx≥1/2
x∈[2kπ-π/3,2kπ+π/3]
综上
x∈[2kπ,2kπ+π/3]
定义域为
{x|x∈[2kπ,2kπ+π/3],k∈z}