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Ch. 2 - Acute Angles and Right Triangles
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 3, Problem 10

Determine whether each statement is true or false. If false, tell why. csc 22° ≤ csc 68°

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1
Recall the definition of the cosecant function: \(\csc \theta = \frac{1}{\sin \theta}\). This means that the value of \(\csc \theta\) depends inversely on \(\sin \theta\).
Since \(\sin \theta\) is positive in the first quadrant (where both 22° and 68° lie), compare \(\sin 22^\circ\) and \(\sin 68^\circ\) to understand the behavior of their cosecants.
Note that \(\sin 22^\circ\) is less than \(\sin 68^\circ\) because sine increases from 0° to 90°, so \(\sin 22^\circ < \sin 68^\circ\).
Because \(\csc \theta = \frac{1}{\sin \theta}\), a smaller sine value corresponds to a larger cosecant value. Therefore, \(\csc 22^\circ > \csc 68^\circ\).
Conclude that the statement \(\csc 22^\circ \leq \csc 68^\circ\) is false, since \(\csc 22^\circ\) is actually greater than \(\csc 68^\circ\).

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Key Concepts

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

Definition and Properties of the Cosecant Function

The cosecant function, csc(θ), is the reciprocal of the sine function, defined as csc(θ) = 1/sin(θ). It is important to understand that csc(θ) is undefined when sin(θ) = 0 and that its values depend inversely on the sine values.
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Graphs of Secant and Cosecant Functions

Behavior of the Sine Function in the First Quadrant

In the first quadrant (0° to 90°), the sine function increases as the angle increases. Therefore, sin(22°) < sin(68°), which directly affects the values of their reciprocals, the cosecants.
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Graph of Sine and Cosine Function

Inequality Relations Involving Reciprocal Functions

When comparing reciprocal functions like cosecant, the inequality reverses relative to the sine values. Since csc(θ) = 1/sin(θ), if sin(22°) < sin(68°), then csc(22°) > csc(68°), which is crucial for determining the truth of the given inequality.
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Introduction to Relations and Functions
Related Practice
Textbook Question

Concept Check Refer to the discussion of accuracy and significant digits in this section to answer the following. WNBA Scorer Women's National Basketball Association player Breanna Stewart of the Seattle Storm was the WNBA's top scorer for the 2018 regular season, with 742 points. Is it appropriate to consider this number between 741.5 and 742.5? Why or why not? (Data from www.wnba.com)

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Textbook Question

Find exact values or expressions for sin A, cos A, and tan A. See Example 1.

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Textbook Question

Concept Check Match each angle in Column I with its reference angle in Column II. Choices may be used once, more than once, or not at all. See Example 1. I. II. 5. A. 45° 6. B. 60° 7. C. 82° 8. D. 30° 9. E. 38° 10. 480° F. 32°

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Textbook Question

Suppose ABC is a right triangle with sides of lengths a, b, and c and right angle at C. Use the Pythagorean theorem to find the unknown side length. Then find exact values of the six trigonometric functions for angle B. Rationalize denominators when applicable. See Example 1. a = 6, c = 7

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Textbook Question

Determine whether each statement is true or false. If false, tell why. tan 60° ≥ cot 40°

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Textbook Question

Suppose ABC is a right triangle with sides of lengths a, b, and c and right angle at C. Use the Pythagorean theorem to find the unknown side length. Then find exact values of the six trigonometric functions for angle B. Rationalize denominators when applicable. See Example 1.

a = 5, b = 12

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