Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Inverse Trigonometric Functions

Question:

If $ sin^{-1}(sin 5) > x^2 - 4x , $ then 

Options:

$x ∈ ( 2 + \sqrt{9-2\pi}, ∞ )$

$x ∈ ( 2 - \sqrt{9-2\pi}, 2+\sqrt{9-2\pi} )$

$x ∈ ( 2 - \sqrt{9-2\pi}, ∞ )$

none of these

Correct Answer:

$x ∈ ( 2 - \sqrt{9-2\pi}, 2+\sqrt{9-2\pi} )$

Explanation:

We have, 

$ sin^{-1}(sin 5) > x^2 - 4x  $

$⇒ sin^{-1}(sin(5-2\pi)) > x^2 - 4 x$

$⇒ 5 - 2 \pi > x^2 - 4x $

$⇒ x^2 - 4x - 5 + 2 \pi < 0 ⇒2 - \sqrt{9-2 \pi} < x < 2 + \sqrt{9-2 \pi}$