2sinxcosx+5cos^2x = 4 решите плииз

2sinxcosx+5cos^2x-4cos^2x-4sin^2x=0

2sinxcosx+cos^2x-4sin^2x=0  | cos^2x

2tgx+1-4tg^2x=0

4tg^2x-2tgx-1=0

tgx=1/4*(1+-sqrt(5))

x=arctg((1+-√5)/4)+Пk