Verified answer

Ola

cos(2x) + cos(x) + 1 = 0

cos(2x( = cos²(x) - sen²(x) = cos²(x) - (1 - cos²(x) = 2cos²(x) - 1

2cos²(x)- 1 + cos(x) + 1 = 0

2cos²(x) + cos(x) = 0

cos(x) *(2cos(x) + 1) = 0

cos(x) = 0 --> x = 90, x = 270

2cos(x) + 1 = 0

cos(x) = - 1/2 --> x = 120 ,x = -120

2senx . cosx - cosx= 0

cos(x) *(2sen(x) - 1) = 0

cos(0) = 0 --> x = 90, x = 270

sen(x) = 1/2 --> x = 30, x = 150

pronto

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