函数y=lg(sinx-cosx/sinx+cosx)的定义域 HELP!>oo

问题描述:

函数y=lg(sinx-cosx/sinx+cosx)的定义域 HELP!>oo

(sinx-cosx)/(sinx+cosx)>0
cosx=0,显然为解,x=kπ+π/2
cosx0,(tgx-1)/(tgx+1)>0---> tgx>1 or tgx kπ+π/4