Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Inverse Trigonometric Functions

Question:

The value of $\sin \left[2 \cot ^{-1}\left(\frac{-5}{12}\right)\right]$ is :

Options:

$\frac{120}{169}$

$\frac{-120}{169}$

$\frac{-60}{169}$

$\frac{60}{169}$

Correct Answer:

$\frac{-120}{169}$

Explanation:

$\sin \left(2 \cot ^{-1} (\frac{-5}{12})\right)$

Let $\theta=\cot ^{-1}(-5 / 12)$

so $\cot \theta=\frac{-5}{12}$

$\sin \theta=\frac{12}{13}$

$\cos \theta=\frac{-5}{13}$

$\sin (2 \theta)$

$=2 \sin \theta \cos \theta$

$=\frac{12}{13} \times \frac{-5}{13} \times 2$

$=\frac{-120}{169}$

Option: 2