cos²(x) = 3 sin²(x)
1 - sin²(x) = 3 sin²(x)
1 = 4 sin²(x)
1/4 = sin²(x)
± √(1/4) = sin(x)
± 1/2 = sin(x)
sin(x) = 1/2 or sin(x) = -1/2
[x = arcsin(1/2) + 2nπ or x = π - arcsin(1/2) + 2nπ]
… … … or [x = arcsin(-1/2) + 2nπ or x = π - arcsin(-1/2) + 2nπ]
(where n is any integer)
[x = π/6 + 2nπ or x = 5π/6 + 2nπ]
… … … or [x = -π/6 + 2nπ or x = 7π/6 + 2nπ]
