If 2 cos 3θ = 1 then θ = ?
Given: 2 cos 3θ = 1
Therefore, cos 3θ = 1/2
⇒ cos 3θ = cos 60°
On comparing both sides, we get:
3θ = 60°
⇒ θ = 60°/3
⇒ θ = 20°