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Ch. 1 - Angles and the Trigonometric Functions
Chapter 1, Problem 1.24a

Use the unit circle shown to find the value of the trigonometric function.
tan 11πœ‹/6

Verified step by step guidance
1
Step 1: Understand that the unit circle is a circle with a radius of 1 centered at the origin of a coordinate plane. The angle 11πœ‹/6 is measured in radians.
Step 2: Convert the angle 11πœ‹/6 to a more familiar angle by subtracting 2πœ‹ (a full circle) from it, since 11πœ‹/6 is greater than 2πœ‹. This will help find the equivalent angle within the first circle rotation.
Step 3: Calculate 11πœ‹/6 - 2πœ‹. Since 2πœ‹ is equivalent to 12πœ‹/6, subtracting gives 11πœ‹/6 - 12πœ‹/6 = -πœ‹/6. This means 11πœ‹/6 is coterminal with -πœ‹/6.
Step 4: Recognize that -πœ‹/6 is equivalent to 11πœ‹/6 on the unit circle, and it corresponds to the reference angle πœ‹/6 in the fourth quadrant.
Step 5: Use the fact that in the fourth quadrant, the tangent function is negative. The reference angle πœ‹/6 has a tangent value of 1/√3, so tan(11πœ‹/6) = -1/√3.

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Key Concepts

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

Unit Circle

The unit circle is a circle with a radius of one centered at the origin of a coordinate plane. It is a fundamental tool in trigonometry, as it allows for the definition of trigonometric functions based on angles measured from the positive x-axis. Each point on the unit circle corresponds to a specific angle and its sine and cosine values, which are essential for calculating other trigonometric functions.
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Introduction to the Unit Circle

Tangent Function

The tangent function, denoted as tan(ΞΈ), is defined as the ratio of the sine and cosine of an angle: tan(ΞΈ) = sin(ΞΈ) / cos(ΞΈ). It represents the slope of the line formed by the angle in the unit circle. Understanding how to derive the tangent from the unit circle is crucial for solving problems involving angles and their corresponding trigonometric values.
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Introduction to Tangent Graph

Angle Measurement in Radians

In trigonometry, angles can be measured in degrees or radians, with radians being the standard unit in mathematical contexts. The angle 11Ο€/6 radians corresponds to 330 degrees, which is important for locating the angle on the unit circle. Recognizing how to convert between radians and degrees is essential for accurately determining the values of trigonometric functions.
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Converting between Degrees & Radians
Related Practice
Textbook Question

In Exercises 5–18, the unit circle has been divided into twelve equal arcs, corresponding to t-values of


0, πœ‹, πœ‹, πœ‹, 2πœ‹, 5πœ‹, πœ‹, 7πœ‹, 4πœ‹, 3πœ‹, 5πœ‹, 11πœ‹, and 2πœ‹.

6 3 2 3 6 6 3 2 3 6


Use the (x,y) coordinates in the figure to find the value of each trigonometric function at the indicated real number, t, or state that the expression is undefined.

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In Exercises 11–18, continue to refer to the figure at the bottom of the previous page.

sec 3πœ‹/2

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Textbook Question

Use the unit circle shown to find the value of the trigonometric function.

cos πœ‹/6

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Textbook Question

Use the unit circle shown to find the value of the trigonometric function.

sin (2πœ‹/3)

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Textbook Question

The unit circle has been divided into eight equal arcs, corresponding to t-values of


0, πœ‹/4, πœ‹/2, 3πœ‹/4, πœ‹, 5πœ‹/4, 3πœ‹/2, 7πœ‹/4, and 2πœ‹.


a. Use the (x,y) coordinates in the figure to find the value of the trigonometric function.

b. Use periodic properties and your answer from part (a) to find the value of the same trigonometric function at the indicated real number.

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sin 3πœ‹/4

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Textbook Question

Find a cofunction with the same value as the given expression.

cos (πœ‹/2)

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Textbook Question

A point P(x, y) is shown on the unit circle corresponding to a real number t. Find the values of the trigonometric functions at t.

<IMAGE>

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