y=1/(2sinx-1),则:2sinx -1≠0,即sinx≠1/2,
则:x≠2kπ+π/6且x≠2kπ+5π/6,其中k∈Z
即:定义域{x/x∈R且x≠2kπ+π/6且x≠2kπ+5π/6,k∈Z }