5sin^2 x + 5sinx*cosx=3
5sin^2x-3,5sinxcosx+2cos^2x-3sin^2x-3cos^2x=0 2sin^2x-cos^2x-3,5sinxcosx=0 2tg^x-3,5tgx-1=0 tgx=-1/4 tgx=2 x=arctg2+Пk x=-arctg(1/4)+Пk.