Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Inverse Trigonometric Functions

Question:

The value of $sin^{-1} (sin 10)$, is

Options:

$3\pi - 10$

$10- 3\pi $

$3\pi + 10$

$4\pi - 10$

Correct Answer:

$3\pi - 10$

Explanation:

We know that $ sin^{-1}(sin \theta) = \theta , $ if $-\frac{\pi}{2} ≤ θ ≤ \frac{\pi}{2}$.

 Here, θ = 10 radians which does not lie between $-\frac{\pi}{2}$ and $\frac{\pi}{2}$.

But, $ 3\pi - \theta $ i.e $3\pi - 10$ lies, netween $-\frac{\pi}{2}$ and $\frac{\pi}{2}$.

Also, $sin(3\pi - 10) = sin 10.$

∴ $ sin^{-1}(sin 10)=sin^{-1}(sin (3\pi - 10))= 3\pi - 10 $