Table of contents
- 0. Review of College Algebra4h 43m
- 1. Measuring Angles39m
- 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 3.65
Textbook Question
Find the approximate value of s, to four decimal places, in the interval [0 , π/2] that makes each statement true.
sec s = 1.0806
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1
Recognize that \( \sec(s) = \frac{1}{\cos(s)} \). Therefore, \( \sec(s) = 1.0806 \) implies \( \frac{1}{\cos(s)} = 1.0806 \).
Rearrange the equation to solve for \( \cos(s) \): \( \cos(s) = \frac{1}{1.0806} \).
Calculate \( \cos(s) \) using the value from the previous step.
Use the inverse cosine function to find \( s \): \( s = \cos^{-1}(\cos(s)) \).
Ensure that the value of \( s \) is within the interval \([0, \frac{\pi}{2}]\).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Secant Function
The secant function, denoted as sec(s), is the reciprocal of the cosine function. It is defined as sec(s) = 1/cos(s). Understanding this relationship is crucial for solving equations involving secant, as it allows us to express sec(s) in terms of cosine, which can then be manipulated to find the angle s.
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Inverse Trigonometric Functions
Inverse trigonometric functions, such as arccosine, are used to find angles when the value of a trigonometric function is known. For example, if sec(s) = 1.0806, we can first find cos(s) and then use the arccos function to determine the angle s. This concept is essential for solving for angles in trigonometric equations.
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Introduction to Inverse Trig Functions
Interval Restrictions
The interval [0, π/2] indicates that we are only considering angles in the first quadrant, where both sine and cosine are positive. This restriction is important because it ensures that the values of the trigonometric functions behave predictably, allowing us to find a unique solution for s within this range.
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