2sin^2x-9 sinx cosx+7 cos^2x=0

[latex]2sin^2x-9sinxcosx+7cos^2x=0, |:cos^2xe 0\\2tg^2x-9tgx+7=0\\(tgx)_1=1,; x_1=frac{pi}{4}+pi n,; nin Z\\(tgx)_2=frac{7}{2},; x_2=arctgfrac{7}{2}+pi n,; nin Z[/latex]