sin2x-12(sinx-cosx)+12=01-（sinx-cosx)^2-12(sinx-cosx)+12=0sinx-cosx=t=√2sin(x-45),属于0到π闭-√2/2<=t<=√2t^2+12t-13=0(t-1)(t+13)=0t=1或t=-13舍t=√2sin(x-∏/4)=1x=∏/2或x=∏
