0.5×sin2x×ctgx-cosx=sin^2x

ctgx=cosx/sinxsin2x=2sinx*cosx0.5*sin2x*ctgx - cosx = sin^2 x0.5*2*sinx*cosx*cosx/sinx - cox = 1 - cos^2 xcos^2 x - cosx - 1 + cos^2 x =02cos^2 x - cosx - 1 = 0cosx = t2t^2 - t - 1 = 0D=1-4*2*(-1)=9t1=1t2=-0.51. cosx=12. cosx=-0.5отсюда находим х