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
1. Measuring Angles
Radians
Problem 18c
Textbook Question
Convert each degree measure to radians. Leave answers as multiples of π. See Examples 1(a) and 1(b). ―315°
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1
Start with the formula to convert degrees to radians: \( \text{radians} = \text{degrees} \times \frac{\pi}{180} \).
Substitute the given degree measure into the formula: \(-315° \times \frac{\pi}{180} \).
Simplify the expression by multiplying \(-315\) by \(\frac{\pi}{180}\).
Factor out the greatest common divisor from \(-315\) and \(180\) to simplify the fraction.
Express the simplified fraction as a multiple of \(\pi\).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Degree to Radian Conversion
To convert degrees to radians, use the formula: radians = degrees × (π/180). This relationship arises from the definition of a radian, which is the angle subtended at the center of a circle by an arc equal in length to the radius. Understanding this conversion is essential for solving problems that require angle measures in different units.
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Understanding π (Pi)
Pi (π) is a mathematical constant approximately equal to 3.14159, representing the ratio of a circle's circumference to its diameter. In trigonometry, π is often used in angle measures, particularly when converting between degrees and radians. Recognizing π as a fundamental part of radian measures is crucial for accurate calculations.
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Negative Angles in Trigonometry
In trigonometry, angles can be positive or negative, with negative angles indicating a clockwise rotation from the positive x-axis. For example, -315° is equivalent to a positive angle of 45° (since -315° + 360° = 45°). Understanding how to interpret and convert negative angles is important for solving trigonometric problems accurately.
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