Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Inverse Trigonometric Functions

Question:

On simplifying $\cot \left(2 \tan ^{-1} x\right)$ where $|x|<1$, we get:

Options:

$\frac{1-x^2}{2 x}$

$\frac{2 x}{1-x^2}$

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

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

Correct Answer:

$\frac{1-x^2}{2 x}$

Explanation:

The correct answer is Option (1) → $\frac{1-x^2}{2 x}$

$\cot \left(2 \tan ^{-1} x\right)=\frac{1}{\tan\left(2 \tan ^{-1} x\right)}$

$=\frac{1}{\tan\left(\tan ^{-1}(\frac{2x}{1-x^2})\right)}=\frac{1-x^2}{2 x}$