sin 4 x - cos 2 x = 0
2 sin 2 x cos 2 x - cos 2 x = 0
cos 2 x ( 2 sin 2 x - 1 ) = 0
cos 2 x = 0
2 x = π/2 + nπ / : 2
x 1 = π/4 + nπ/2, n ∈ Z
2 sin 2 x - 1 = 0
2 sin 2 x = 1
sin 2 x = 1/2
2 x = π/6 + 2 nπ
2 x = 5π/6 + 2 nπ
x 2 = π/12 + nπ
x 3 = 5π/12 + nπ , n ∈ Z
