6*sin^2x+sinx*cosx-cos^2x=0

6sin^2x+sinxcosx-cos^2x-2sin^2x-2cos^2x=0

4sin^2x+sinxcosx-3cos^2x=0 :cos^2x

4tg^2x+tgx-3=0

tgx=-1

tgx=3/4

x=arctg3/4+Пk

x=-П/4+Пk