Решите уравнение! 2 соs^2x+cos2x=0

Question

Решите уравнение!
2 соs^2x+cos2x=0

Answer 1

Cos2x(2cosx+1)
cos2x=0
x= Pi/2+Pin,n z

2cosx+1=0
2cosx=-1
cosx=-1/2
x=+- arccos(-1/2)+2pin n z
x=+- (Pi-arccos(1/2)) + 2Pin n z
x=+- (Pi-Pi/3)+2pin n z
x=+-(3Pi/3-Pi/3)+2Pin n z
x=+- 2Pi/3+2Pin n z