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
Reference Angles
2:58 minutes
Problem 52a
Textbook Question
Textbook QuestionIn Exercises 35–60, find the reference angle for each angle. 553°
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reference Angle
The reference angle is the acute angle formed by the terminal side of a given angle and the x-axis. It is always measured as a positive angle and is typically between 0° and 90°. For angles greater than 360°, the reference angle can be found by first reducing the angle to its equivalent within the first full rotation (0° to 360°).
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Angle Reduction
Angle reduction involves converting an angle greater than 360° into an equivalent angle within the standard range of 0° to 360°. This is done by subtracting 360° from the angle until it falls within the desired range. For example, for 553°, you would subtract 360° once to find its equivalent angle of 193°.
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Quadrants
The coordinate plane is divided into four quadrants, each corresponding to specific ranges of angles. The first quadrant contains angles from 0° to 90°, the second from 90° to 180°, the third from 180° to 270°, and the fourth from 270° to 360°. The location of the terminal side of the angle determines how to calculate the reference angle, as it will affect the acute angle formed with the x-axis.
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