Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
1. Equations & Inequalities
Rational Equations
2:16 minutes
Problem 27b
Textbook Question
Textbook QuestionSolve each problem. Circumference of a CircleThe circumference of a circle varies directly as the radius. A circle with radius 7 in. has circumference 43.96 in. Find the circumference of the circle if the radius changes to 11 in.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Direct Variation
Direct variation describes a relationship between two variables where one variable is a constant multiple of the other. In this case, the circumference (C) of a circle varies directly with its radius (r), meaning C = k * r, where k is a constant. This concept is essential for understanding how changes in the radius affect the circumference.
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Circumference of a Circle
The circumference of a circle is the distance around it and can be calculated using the formula C = 2πr, where r is the radius. This formula highlights the relationship between the radius and the circumference, reinforcing the concept of direct variation. Knowing this formula allows for the calculation of circumference when the radius is known.
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Proportional Relationships
Proportional relationships occur when two quantities maintain a constant ratio. In the context of this problem, as the radius increases, the circumference increases proportionally. Understanding this relationship is crucial for solving the problem, as it allows for the use of ratios to find the new circumference based on the change in radius.
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