NTA Abhyas JEE Main2020MathematicsInverse Trigonometric FunctionsPractice
If x ∈ 0 , 1 , then the value of 2 tan - 1 1 - x 2 2 x + 2 cos - 1 1 - x 2 1 + x 2 is equal to
Options
- A- π 2
- B0
- Cπ 2
- Dπ
Correct answer
D. π
Step-by-step solution
∴ Let y = 2 tan - 1 ⁡ 1 - x 2 2 x + 2 cos - 1 ⁡ 1 - x 2 1 + x 2 Putting x = tan ⁡ θ As, x ∈ 0,1 ,   θ ∈ 0 , π 4 and π 2 - 2 θ ∈ 0 , π 2 ∴ y = 2 tan - 1 ⁡ cot ⁡ 2 θ + 2 cos - 1 ⁡ cos ⁡ 2 θ = 2 tan - 1 ⁡ tan ⁡ π 2 - 2 θ + 2 cos - 1 ⁡ cos ⁡ 2 θ = 2 π 2 - 2 θ + 4 θ = π