pt<=>(1+sin2x)(sinx+cosx)=sinx+cosx+2cosx<=>(1+sin2x−1)(sinx+cosx)=2cosx<=>2sinx.cosx(sinx+cosx)=2cosx<=>cosx(sin2x+sinx.cosx−1)=0<=>cosx(cos2x+sinx.cosx)=0<=>cos2x(sinx+cosx)=0<=>√2cos2xsin(x+π4)=0XONG
pt<=>(1+sin2x)(sinx+cosx)=sinx+cosx+2cosx<=>(1+sin2x−1)(sinx+cosx)=2cosx<=>2sinx.cosx(sinx+cosx)=2cosx<=>cosx(sin2x+sinx.cosx−1)=0<=>cosx(cos2x+sinx.cosx)=0<=>cos2x(sinx+cosx)=0$<=>\sqrt2cos^2x.sin(x+\frac{\pi}4)=0$$XONG$