cosx=cos²(x/2)-sin²(x/2)所以f(x)=2√2[cos²(x/2)-sin²(x/2)]/[cos(x/2)-sin(x/2)]=2√2[cos(x/2)+sin(x/2)]=2√2[√2*sin(x/2+π/4)]=4sin(x/2+π/4)sinx增区间是(2kπ-π/2,2kπ+π/2)减区间...