NTA Abhyas JEE Main2020MathematicsTrigonometric EquationsPractice
The set   x ∈ R : cos ⁡ 2 x + 2 cos 2 ⁡ x = 2   is equal to
Options
- A2 n π + π 3 : n ∈ Z
- Bn π ± π 6 : n ∈ Z
- Cn π + π 3 : n ∈ Z
- D2 n π - π 3 : n ∈ Z
Correct answer
B. n π ± π 6 : n ∈ Z
Step-by-step solution
Given, 2 cos 2 x - 1 + 2 cos 2 x = 2 ⇒ cos 2 x = 3 4 cos 2 x = cos 2 π 6 ∴ x = n π ± π 6 : n ∈ Z