COSx>1/2 cosx-0,5-sinx=1/2 cosx-sinx=1 1-2sinxcosx=1 sin2x=0 x=пk/2 -п/3+2Пk<=x<=П/3+2пk x=2Пk cosx<1/2 0,5-cosx-sinx=1/2 cosx=-sinx tgx=-1 x=-п/4+пk П/3+2Пk<x<5П/3+2Пk x=-П/4+(2k+1)П