NTA Abhyas JEE Main2020MathematicsFunctionsPractice
If the function f : R → A defined as f x = sin - 1 ⁡ x 1 + x 2 is a surjective function, then the set A is
Options
- A– π 6 , π 6
- B– π 2 , π 2
- C– π 3 , π 6
- D0 , π 3
Correct answer
A. – π 6 , π 6
Step-by-step solution
Let y = x 1 + x 2 ⇒ y x 2 - x + y = 0 ∵ x ∈ R , hence D ≥ 0 ⇒ - 1 2 - 4 y 2 ≥ 0 ⇒ y ∈ - 1 2 , 1 2 i.e. sin - 1 ⁡ y ∈ sin - 1 ⁡ - 1 2 , sin - 1 ⁡ 1 2 Hence, the range of f x ∈ - π 6 , π 6 ≡ A