Объяснение:
3sin^2 x -2,5*2sinx*cosx +1=0, 3sin^2 x-5sinxcosx+sin^2 x +cos^2 x=0,
4sin^2x-5sinxcosx +cos^2 x=0, делим на cos^2 x , cosx не = 0,
4tg^2 x-5tgx +1=0, tgx=-1, tgx=-1/4, x=-p/4 +pn, x=-arctg 1/4 +pn,
n E Z
