NTA Abhyas JEE Main2020MathematicsInverse Trigonometric FunctionsPractice
If cos - 1 x - x 2 2 + x 3 4 - … + sin - 1 x 2 - x 4 2 + x 6 4 - … = π 2 for 0 < x < 2 , then x is equal to
Correct answer
1
Step-by-step solution
Since, sin - 1 x + cos - 1 x = π 2 for x ≤ 1 . ∴ x - x 2 2 + x 3 4 - … = x 2 - x 4 2 + x 6 4 - … ⇒ x 1 + x 2 = x 2 1 + x 2 2 0 < x < 2 ⇒ x 2 + x = x 2 2 + x 2 ⇒ 2 x + x 3 = 2 x 2 + x 3 ⇒ x 2 = x ⇒ x = 0 , 1 But x 2 = x ≠ 0 , ∴ x = 1 .