Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Inverse Trigonometric Functions

Question:

The value of $cos \left[tan^{-1}\begin{Bmatrix}sin(cot^{-1}x\end{Bmatrix}\right]$= 

Options:

$\sqrt{\frac{x^2+2}{x^2+3}}$

$\sqrt{\frac{x^2+2}{x^2+1}}$

$\sqrt{\frac{x^2+1}{x^2+2}}$

none of these

Correct Answer:

$\sqrt{\frac{x^2+1}{x^2+2}}$

Explanation:

We have, 

$cos \left[tan^{-1}\begin{Bmatrix}sin(cot^{-1}x\end{Bmatrix}\right]$

$= cos \begin{Bmatrix} tan^{-1} \frac{1}{\sqrt{1+x^2}}\end{Bmatrix}=\frac{\sqrt{1+x^2}}{\sqrt{2+x^2}}=\sqrt{\frac{1+x^2}{2+x^2}}$