Question

трегонометрическое уравнение
3 соs^2x+5sinx+5=0

Answer 1

$3-3sin^2x+5sinx+5=0 \ 3sin^2x-5sinx-8=0 \ \ sinx=y ; \ |y| leq 1 \\ 3y^2-5y-8=0 \ D=25+4*3*8=121 \ y_1= frac{5-11}{6}=-1 \ \ y_2= frac{5+11}{6} = frac{16}{6} geq 1$

$sinx=-1 \ x=- frac{pi}{2}+2pi n$, n∈z