5sin^2x-14sinxcosx-3cos^x=2

2sin2x−5sinxcosx−cos2x=−2=>2sin2x−5sinxcosx−cos2x+2=02sin2x−5sinxcosx−cos2x+2sin2x+2cos2x=0=>4sin2x−5sinxcosx+cos2x=0cos2x(4tg2x−5x+1)=0=>