NTA Abhyas JEE Main2020MathematicsInverse Trigonometric FunctionsPractice
The value(s) of x satisfying the equation sin - 1 1 - x - 2 sin - 1 x = π 2 is/are
Options
- A0
- B1 2
- C0 , 1 2
- D- 1 2
Correct answer
A. 0
Step-by-step solution
We have, sin - 1 1 - x - 2 sin - 1 x = π 2 ⇒ sin - 1 1 - x = π 2 + 2 sin - 1 x ⇒ 1 - x = sin π 2 + 2 sin - 1 x ⇒ 1 - x = cos 2 sin - 1 x ⇒ 1 - x = cos cos - 1 1 - 2 x 2 ∵ 2 sin - 1 x = cos - 1 1 - 2 x 2 ⇒ 1 - x = 1 - 2 x 2 ⇒ x = 2 x 2 ⇒ x 2 x - 1 = 0 ⇒ x = 0 , 1 2 For, x = 1 2 , we have LHS = sin - 1 1 - x - 2 sin - 1 x = sin - 1 1 2 - 2 sin - 1 1 2 = - sin - 1 1 2 = - π 6 ≠ R . H . S . So, x = 1 2 is not a root of the given equation. Clearly, x = 0 satisfies the equation Here, x =