(cosx+sinx)/=[sin(Pi/4)cosx + cos(Pi/4)sinx]/=sin(Pi/4 +x)/cos(Pi/4 +x)=tan(x+ Pi/4)所以f（x）的最小正周期是 T=Pi (cosx+sinx)=√2[（√2/2 )cosx+ (√2/2) sinx]=√2[sin(Pi/4)cosx+cos(Pi/4)sinx]=√2 sin(...