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Ch. 2 - Graphs of the Trigonometric Functions; Inverse Trigonometric Functions
Chapter 2, Problem 19

In Exercises 1–26, find the exact value of each expression. _ cot⁻¹ √3

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1
Recognize that \( \cot^{-1}(x) \) is the inverse cotangent function, which gives the angle whose cotangent is \( x \).
Recall that \( \cot(\theta) = \frac{1}{\tan(\theta)} \). Therefore, if \( \cot(\theta) = \sqrt{3} \), then \( \tan(\theta) = \frac{1}{\sqrt{3}} \).
Identify the angle \( \theta \) for which \( \tan(\theta) = \frac{1}{\sqrt{3}} \). This is a common angle in trigonometry.
Recall that \( \tan(\frac{\pi}{6}) = \frac{1}{\sqrt{3}} \). Therefore, \( \theta = \frac{\pi}{6} \).
Conclude that \( \cot^{-1}(\sqrt{3}) = \frac{\pi}{6} \).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Inverse Trigonometric Functions

Inverse trigonometric functions, such as cot⁻¹, are used to find angles when given a trigonometric ratio. For example, cot⁻¹(x) gives the angle whose cotangent is x. Understanding these functions is crucial for solving problems that require angle determination from known ratios.
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Cotangent Function

The cotangent function is defined as the ratio of the adjacent side to the opposite side in a right triangle, or as the reciprocal of the tangent function. Specifically, cot(θ) = 1/tan(θ). Knowing the values of cotangent for common angles helps in finding exact values for inverse cotangent expressions.
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Special Angles in Trigonometry

Special angles, such as 30°, 45°, and 60°, have known trigonometric values that are often used in calculations. For instance, cot(30°) = √3 and cot(60°) = 1/√3. Recognizing these angles and their corresponding values is essential for quickly determining the exact values of trigonometric expressions.
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