2+2sin(2x)-(cos(2x))^2不=0,
1+2sin(2x)+(sin((2x))^2不=0,
[sin(2x)+1]^2不=0,
sin(2x)不=-1,
2x不=2kπ+π,(k為整數(shù))
x不=kπ+π/2.(k為整數(shù))
所以f(x)的定義域?yàn)椋簕x| x不=kπ+π/2,k為整數(shù)}.若 f(x)=2,且x大于-π/4小于3π/4,求x的值這是另一問(wèn)題了。