Question

решите уравнение :

4 cos^2 x - 1 = 0

Answer 1

4cos²x-1=0
cos²x = 1/4
cos(x)= 1/2                  cos(x) = -1/2
x=±π/3+2πn, n ∈ Z     x=±2π/3 + 2πn, n ∈ Z