Which of the following correctly expresses the conversion from rectangular coordinates to cylindrical coordinates ?
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
Polar Coordinate System
Problem 25
Textbook Question
In Exercises 21–40, eliminate the parameter t. Then use the rectangular equation to sketch the plane curve represented by the given parametric equations. Use arrows to show the orientation of the curve corresponding to increasing values of t. (If an interval for t is not specified, assume that −∞ < t < ∞. _ x = √t, y = t − 1
Verified step by step guidance1
Start with the given parametric equations: \(x = \sqrt{t}\) and \(y = t - 1\).
Express \(t\) in terms of \(x\) from the first equation: since \(x = \sqrt{t}\), then \(t = x^2\) (note that \(x \geq 0\) because square roots are non-negative).
Substitute \(t = x^2\) into the second equation to eliminate the parameter: \(y = x^2 - 1\).
Recognize that the rectangular equation is \(y = x^2 - 1\), which is a parabola opening upwards, shifted down by 1 unit.
To sketch the curve, plot the parabola \(y = x^2 - 1\) for \(x \geq 0\) (since \(x = \sqrt{t}\) implies \(x \geq 0\)), and use arrows pointing in the direction of increasing \(t\) (which corresponds to increasing \(x\) and \(y\) values).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Parametric Equations and Parameters
Parametric equations express the coordinates of points on a curve as functions of a parameter, often denoted as t. Understanding how the parameter t controls the position on the curve is essential for analyzing the curve's shape and orientation.
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Eliminating the Parameter
Eliminating the parameter involves rewriting the parametric equations to form a single rectangular equation in terms of x and y. This process helps to identify the curve's equation in the Cartesian plane, making it easier to analyze and sketch.
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Sketching and Orientation of Curves
Sketching the curve requires plotting points that satisfy the rectangular equation and indicating the direction of increasing parameter t with arrows. Orientation shows how the curve is traced as t increases, which is important for understanding the curve's behavior.
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