Find exact values or expressions for sin A, cos A, and tan A. See Example 1.
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
3. Unit Circle
Defining the Unit Circle
Problem 10
Textbook Question
Determine whether each statement is true or false. If false, tell why. csc 22° ≤ csc 68°
Verified step by step guidance1
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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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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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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