In Exercises 49–58, convert each rectangular equation to a polar equation that expresses r in terms of θ. x² + y² = 9
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 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
9. Polar Equations
Convert Equations Between Polar and Rectangular Forms
Problem 5.3.59
Textbook Question
In Exercises 59–74, convert each polar equation to a rectangular equation. Then use a rectangular coordinate system to graph the rectangular equation. r = 8
Verified step by step guidance1
Recall the relationship between polar and rectangular coordinates: \(x = r \cos\theta\) and \(y = r \sin\theta\), and also \(r^2 = x^2 + y^2\).
Given the polar equation \(r = 8\), square both sides to express in terms of \(r^2\): \(r^2 = 8^2\) which simplifies to \(r^2 = 64\).
Substitute \(r^2\) with \(x^2 + y^2\) to convert the equation into rectangular form: \(x^2 + y^2 = 64\).
Recognize that the rectangular equation \(x^2 + y^2 = 64\) represents a circle centered at the origin with radius 8.
To graph the equation, draw a circle centered at the origin \((0,0)\) with radius 8 units on the rectangular coordinate system.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Polar and Rectangular Coordinate Systems
Polar coordinates represent points using a radius and an angle (r, θ), while rectangular coordinates use x and y values. Understanding how these systems describe points in the plane is essential for converting equations between them.
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Intro to Polar Coordinates
Conversion Formulas Between Polar and Rectangular Coordinates
The key formulas for conversion are x = r cos θ and y = r sin θ, with r = √(x² + y²). These allow translating polar equations into rectangular form by substituting r and θ with expressions involving x and y.
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Convert Points from Polar to Rectangular
Graphing Rectangular Equations
Once the polar equation is converted, graphing involves plotting the rectangular equation on the Cartesian plane. Recognizing the shape (e.g., circle, line) from the rectangular form helps in accurately sketching the graph.
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Convert Equations from Polar to Rectangular
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