NTA Abhyas JEE Main2020MathematicsTrigonometric Ratios & IdentitiesPractice
If sin 6 θ + cos 6 θ + k cos 2 2 θ = 1, then k is equal to
Options
- A1 2 tan 2 2 θ
- B1 4 tan 2 2 θ
- C4 cot 2 2 θ
- D3 4 tan 2 2 θ
Correct answer
D. 3 4 tan 2 2 θ
Step-by-step solution
sin 2 θ + cos 2 θ sin 4 θ - sin 2 θ cos 2 θ + cos 4 θ + k cos 2 2 θ = 1 or sin 2 θ + cos 2 θ 2 - 3 sin 2 θ cos 2 θ + k cos 2 2 θ = 1 or 1 - 3 sin 2 θ cos 2 θ + k cos 2 2 θ = 1 or k cos 2 2 θ = 3 sin 2 θ cos 2 θ or k cos 2 2 θ = 3 4 2 sin θ cos θ 2 or k cos 2 2 θ = 3 4 sin 2 2 θ or k = 3 4 tan 2 2 θ