Sin^2 5П/6 × sin2x + cos2x +1 =0
(1/4)sin2x + cos2x+1=0
(1/4)*2sinx*cosx+(cos^2x-sin^2x)+(cos^2x+sin^2x)=0
(1/2)sinx*cosx +2cos^2x=0
cosx*((1/2)sinx+2cosx)=0
cosx=0 ⇒ [b] x=(π/2)+πk, k ∈ Z[/b]
или
(1/2)sinx+2cosx=0
tgx=-4
x=arctg(-4)+πn, n ∈ Z
[b]x=-arctg4+πn, n ∈ Z[/b]