1+ctg2x=1\cos(3п\2-2x)

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