Question

_Алгебра_ Решите уравнение

Answer 1

$2sin^2x-9sinxcosx+7cos^2x=0 \ 2*frac{sin^2x}{cos^2x} -9* frac{sinx}{cosx} +7=0 \2tg^2x-9tgx+7=0 \tgx=y \2y^2-9y+7=0 \D=81-56=25=5^2 \y_1= frac{9+5}{4}= frac{14}{4} =3,5 \y_2= frac{9-5}{4} =1 \tgx=3,5 \x_1=arctg(3,5)+pi n, n in Z \tgx=1 \x_2= frac{pi}{4} +pi n, n in Z$