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