Target Exam

CUET

Subject

Section B1

Chapter

Continuity and Differentiability

Question:

The function $f(x) = \cot x$ is discontinuous on the set

Options:

$\{x = n\pi : n \in \mathbb{Z}\}$

$\{x = 2n\pi : n \in \mathbb{Z}\}$

$\left\{x = (2n + 1)\frac{\pi}{2} : n \in \mathbb{Z}\right\}$

$\left\{x = \frac{n\pi}{2} : n \in \mathbb{Z}\right\}$

Correct Answer:

$\{x = n\pi : n \in \mathbb{Z}\}$

Explanation:

The correct answer is Option (1) → $\{x = n\pi : n \in \mathbb{Z}\}$ ##

We know that, $f(x) = \cot x$ is continuous in $R - \{x = n\pi \in \mathbb{Z}\}$.

Since, $f(x) = \cot x = \frac{\cos x}{\sin x} \quad [∵\sin x = 0 \text{ at } x = n\pi, n \in \mathbb{Z}]$

Hence, $f(x) = \cot x$ is discontinuous on the set $\{x = n\pi : n \in \mathbb{Z}\}$.