1+ctg2x=1\cos(3п\2-2x)

1+ctg2x=-1/sin2xsin2x/sin2x + cos2x/sin2x + 1/ sin2x =0sin2x+cos2x+1=0cos^2 x - sin^2 x +2 sinxcosx+ cos^2x + sin^2x=02sinxcosx+2cos^2x=02cosx(sinx+1)=0cosx=0x=П/2 +Пn sinx=-1x= -- П/2 +Пn