Помогите cosx + sin(1,5Пи + 2x)=0

Question

Помогите
cosx + sin(1,5Пи + 2x)=0

Answer 1

CosX+sin(3π/2+2x)=0
cosx-cos2x=0
cosx-2cos²x+1=0
2cos²x-cosx-1=0
D=9; √D=3
cosx=-1/2
x=+ - 2π/3+2πn, n € Z
cosx=1
x=2πn, n € Z