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 = 1 + 3 cos t, y = 2 + 3 sin t; 0 ≤ t < 2π
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 71
Textbook Question
In Exercises 71–76, eliminate the parameter and graph the plane curve represented by the parametric equations. Use arrows to show the orientation of each plane curve. x = 2t − 1, y = 1 − t; −∞ < t < ∞
Verified step by step guidance1
Identify the given parametric equations: \(x = 2t - 1\) and \(y = 1 - t\) with parameter \(t\) ranging over all real numbers.
Solve one of the parametric equations for \(t\) in terms of \(x\) or \(y\). For example, from \(x = 2t - 1\), solve for \(t\): \(t = \frac{x + 1}{2}\).
Substitute the expression for \(t\) into the other parametric equation to eliminate the parameter. Substitute \(t = \frac{x + 1}{2}\) into \(y = 1 - t\) to get \(y\) in terms of \(x\).
Simplify the resulting equation to express \(y\) explicitly as a function of \(x\), which will give the Cartesian equation of the curve.
To determine the orientation of the curve, consider how \(x\) and \(y\) change as \(t\) increases. For example, calculate a few points for increasing values of \(t\) and plot arrows on the graph to indicate the direction of increasing \(t\).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Parametric Equations
Parametric equations express the coordinates of points on a curve as functions of a parameter, usually denoted as t. Instead of y as a function of x, both x and y depend on t, allowing the description of more complex curves and motions.
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Eliminating the Parameter
Eliminating the parameter involves rewriting the parametric equations to express y directly in terms of x, removing t. This is done by solving one equation for t and substituting into the other, resulting in a Cartesian equation that describes the same curve.
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Orientation of Parametric Curves
Orientation indicates the direction in which the curve is traced as the parameter increases. Using arrows on the graph shows this direction, which is important for understanding the behavior and properties of the curve over the parameter's domain.
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