Question

3cos2x-7sin=4
Помогите решить

Answer 1

$cos{2x}=1-2sin^2x \ 3*(1-2sin^2x)-7sinx-4=0 \ 3-6sin^2x-7sinx-4=0 \ 6sin^2x+7sinx+1=0 \ sinx=t \ 6t^2+7t+1=0 \ t_1=- frac{1}{6} \ t_2= -1 \ left { {{sinx=-1} atop {sinx=-frac{1}{6} }} right. left { {{x_1= frac{3 pi }{2}+2pi n } atop {x_2=arcsin(-frac{1}{6})+2pi n }}atop {x_3= pi+arcsin(-frac{1}{6})+2pi n }} right.$