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Ch. 1 - Angles and the Trigonometric Functions
Chapter 1, Problem 1.1

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.
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1
Identify the coordinates of the point P(x, y) on the unit circle.
Recall that on the unit circle, the x-coordinate of point P corresponds to \( \cos(t) \) and the y-coordinate corresponds to \( \sin(t) \).
Use the coordinates to determine \( \cos(t) = x \) and \( \sin(t) = y \).
Calculate \( \tan(t) \) using the formula \( \tan(t) = \frac{\sin(t)}{\cos(t)} = \frac{y}{x} \), provided \( x \neq 0 \).
Determine the remaining trigonometric functions: \( \csc(t) = \frac{1}{\sin(t)} \), \( \sec(t) = \frac{1}{\cos(t)} \), and \( \cot(t) = \frac{1}{\tan(t)} = \frac{x}{y} \), provided \( y \neq 0 \).

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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 fundamental in trigonometry as it provides a geometric representation of the sine and cosine functions. Any point on the unit circle can be expressed as (cos(t), sin(t)), where t is the angle formed with the positive x-axis, allowing for easy calculation of trigonometric values.
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Introduction to the Unit Circle

Trigonometric Functions

Trigonometric functions, including sine, cosine, and tangent, relate the angles of a triangle to the lengths of its sides. On the unit circle, the sine of an angle corresponds to the y-coordinate, while the cosine corresponds to the x-coordinate of a point on the circle. Understanding these functions is essential for evaluating trigonometric values at specific angles.
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Introduction to Trigonometric Functions

Angle Measurement

Angles in trigonometry can be measured in degrees or radians, with radians being the standard unit in mathematical contexts. The relationship between the two is that 180 degrees is equivalent to π radians. Knowing how to convert between these units is crucial for accurately determining the trigonometric functions at a given angle t, especially when working with the unit circle.
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Reference Angles on the Unit Circle
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, 𝜋, 𝜋, 2𝜋, 5𝜋, 𝜋, 7𝜋, 4𝜋, 3𝜋, 5𝜋, 11𝜋, and 2𝜋.

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 11𝜋/6

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Textbook Question
In Exercises 1–4, the graph of a tangent function is given. Select the equation for each graph from the following options: y = tan(x + π/2), y = tan(x + π), y = −tan(x − π/2).

328
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Textbook Question

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


0, 𝜋, 𝜋, 𝜋, 2𝜋, 5𝜋, 𝜋, 7𝜋, 4𝜋, 3𝜋, 5𝜋, 11𝜋, and 2𝜋.

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.

csc 7𝜋/6

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Textbook Question

Use the given triangles to evaluate each expression. If necessary, express the value without a square root in the denominator by rationalizing the denominator.


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csc 45°

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Textbook Question

Use the given triangles to evaluate each expression. If necessary, express the value without a square root in the denominator by rationalizing the denominator.


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tan 𝜋/3

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