1-tanx≠0
由1-tanx≠0,得x≠kπ+π/4,k∈Z,
又由正切的定义可知,x≠2kπ+π/2,k∈Z,
∴函数的定义域为{x∈R| x≠kπ+π/4,且x≠2kπ+π/2,k∈Z }