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Cotangent Function

Definition

Definition of the Cotangent Function

In a right triangle, let θ\theta be an acute angle, then cotangent is defined as:

cotθ=adjacentopposite\cot \theta = \frac{\text{adjacent}}{\text{opposite}}

where “adjacent” refers to the side adjacent to angle θ\theta, and “opposite” refers to the side opposite to angle θ\theta.

符号说明
SymbolTypePronunciation/ExplanationMeaning in This Definition
θ\thetaGreek letterTheta (theta)Represents the measure of an angle (acute angle)

Properties

  • Domain: xkπx \neq k\pi
  • Range: R\mathbb{R}
  • Period: π\pi
  • Parity: Odd function
  • Monotonicity: Decreasing in each monotonic interval
  • Symmetry: Symmetric about the origin

Graph

Exercises

Exercise1

Find the domain and range of y=cotxy = \cot x.

Answer and Explanation (3 个标签)
cotangent function domain range

Domain: xkπx \neq k\pi; Range: R\mathbb{R}.

Exercise2

Determine the periodicity and parity of y=cotxy = \cot x.

Answer and Explanation (3 个标签)
cotangent function period parity

Period is π\pi, it is an odd function.

Exercise3

【2018·Mathematics 3】Which of the following functions are odd functions? (A) y=sinxy = \sin x (B) y=cosxy = \cos x (C) y=cotxy = \cot x (D) y=x2y = x^2

Answer and Explanation (5 个标签)
sine function cosine function cotangent function odd function even function

(A), (C) are odd functions, (B), (D) are not.

Summary

Symbols Appearing in This Article

SymbolTypePronunciation/ExplanationMeaning in This Article
π\piGreek letterPi (pie)Pi, used to represent the period of the cotangent function (π\pi)

Bilingual Glossary

Chinese TermEnglish TermPhoneticExplanation
余切函数cotangent function/kəʊˈtændʒənt ˈfʌŋkʃən/One of the trigonometric functions, denoted as cotx\cot x
余切cotangent/kəʊˈtændʒənt/Function name, abbreviated as cot\cot
周期period/ˈpɪəriəd/The smallest interval at which function values repeat
定义域domain/dəʊˈmeɪn/The range of values for the independent variable

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