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Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Not the one you use?Change textbook
Chapter 5, Problem 71

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 < ∞

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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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