sin²x - 3cosx - 3 = 0
1 - cos²x - 3cosx - 3 = 0
cos²x + 3cosx +2 = 0
cosx = t
t² + 3t + 2 = 0
D = 9 - 8 = 1
t1 = 0.5( - 3 - 1) = -2 не подходит, так как t = соsx ≤1
t2 = 0.5( -3 + 1) = -1
cosx = -1
x = π + 2πk k∈Z
cosx + sin2x = 0
cosx + 2 cosx · sinx = 0
cosx (1 + 2sinx) = 0
1) cosx = 0
x1 = π/2 + πk k∈Z
2) 1 + 2sinx = 0
2sinx = -1
sinx = -1/2
x2 = -π/2 + 2πk k∈Z
x3 = -5π/6 + 2πk k∈z