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
3:47 minutes
Problem 18a
Textbook Question
Textbook QuestionFind the length of the arc on a circle of radius 10 feet intercepted by a 135° central angle. Express arc length in terms of 𝜋. Then round your answer to two decimal places.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Arc Length Formula
The arc length of a circle can be calculated using the formula L = rθ, where L is the arc length, r is the radius, and θ is the central angle in radians. To use this formula, it's essential to convert degrees to radians by multiplying the degree measure by π/180. This relationship allows for the calculation of the arc length based on the circle's radius and the angle subtended at the center.
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Conversion from Degrees to Radians
To apply the arc length formula, angles must be in radians. The conversion from degrees to radians is done using the formula radians = degrees × (π/180). For example, a 135° angle converts to 135 × (π/180) = 3π/4 radians. Understanding this conversion is crucial for accurately calculating the arc length.
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Circumference of a Circle
The circumference of a circle is the total distance around it, calculated using the formula C = 2πr, where r is the radius. Knowing the circumference helps in understanding the relationship between the arc length and the total circle. The arc length is a fraction of the circumference, determined by the ratio of the central angle to 360°, which is essential for interpreting the results of the arc length calculation.
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