In Exercises 9–20, use point plotting to graph the plane curve described by the given parametric equations. Use arrows to show the orientation of the curve corresponding to increasing values of t. x = 2t, y = |t − 1|; −∞ < t < ∞
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
10. Parametric Equations
Graphing Parametric Equations
Problem 30
Textbook Question
Graph each plane curve defined by the parametric equations for t in [0, 2π] Then find a rectangular equation for the plane curve. See Example 3.
x = 2 cos t , y = 2 sin t
Verified step by step guidance1
Identify the given parametric equations: \(x = 2 \cos t\) and \(y = 2 \sin t\), where \(t\) ranges from \(0\) to \(2\pi\).
Recall the Pythagorean identity: \(\cos^2 t + \sin^2 t = 1\). This identity will help us eliminate the parameter \(t\) to find a rectangular equation.
Express \(\cos t\) and \(\sin t\) in terms of \(x\) and \(y\): from \(x = 2 \cos t\), we get \(\cos t = \frac{x}{2}\); from \(y = 2 \sin t\), we get \(\sin t = \frac{y}{2}\).
Substitute these expressions into the Pythagorean identity: \(\left(\frac{x}{2}\right)^2 + \left(\frac{y}{2}\right)^2 = 1\).
Simplify the equation to get the rectangular form: \(\frac{x^2}{4} + \frac{y^2}{4} = 1\), which represents the equation of the curve in the \(xy\)-plane.
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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, often 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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Graphing Parametric Curves
To graph parametric curves, plot points (x(t), y(t)) for values of t within the given interval. This approach helps visualize the path traced by the parameter, revealing shapes like circles, ellipses, or other plane curves.
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Converting Parametric to Rectangular Equations
Converting parametric equations to a rectangular form involves eliminating the parameter t to find a direct relationship between x and y. For trigonometric parametrics like x = 2 cos t and y = 2 sin t, using identities such as cos²t + sin²t = 1 helps derive the rectangular equation.
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Convert Equations from Rectangular to Polar
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