Решить уравнение:4sin^2 х+cosx-3=0

1-4cos^2(x)-cos(x)=0                                                                                    cos(x)=y                                                                                                       y^2+(2/8)x=1/4  y^2+(2/8)x+1/64=17/64                                                                           y1=-1/8(1-sqrt(17))                                                                                                                       y2=-1/8(1+sqrt(17))                                                                                                                          х1=arccos(-1/8(1-sqrt(17)))+2pi*k                                                                x2=arccos(1/8(1-sqrt(17)))+2pi*k                                                      х1=arccos(-1/8(1+sqrt(17)))+2pi*k                                                             х1=arccos(1/8(1+sqrt(17)))+2pi*k                                               k-любое целое