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10.6 Parametric Equations

Describing a curve by x(t) and y(t), eliminating the parameter for a rectangular equation, and parameterizing in reverse.

Algebra and Trigonometry 2e, 10.6 Parametric Equations

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34 exercises

10.6 Exercise 4

Parameterize the curve given by x= y 3 −2y. x = y^{3} - 2 y .

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Eliminating the Parameter in Polynomials

Given x(t)= t 2 +1 x \left(t\right) = t^{2} + 1 and y(t)=2+t, y \left(t\right) = 2 + t , eliminate the parameter, and write the parametric equations as a Cartesian equation.

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10.6 Exercise 7

Given the equations below, eliminate the parameter and write as a rectangular equation for y y as a function of x. x .

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Eliminating the Parameter in Exponential Equations

Eliminate the parameter and write as a Cartesian equation: x(t)= e −t x \left(t\right) = e^{- t} and y(t)=3 e t y \left(t\right) = 3 e^{t}

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Eliminating the Parameter in Logarithmic Equations

Eliminate the parameter and write as a Cartesian equation: x(t)= t +2 x \left(t\right) = \sqrt{t} + 2 and y(t)=log(t). y \left(t\right) = \log \left(t\right) .

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10.6 Exercise 10

Eliminate the parameter and write as a rectangular equation.

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10.6 Exercise 12

Eliminate the parameter from the given pair of parametric equations and write as a Cartesian equation: x(t)=2cost x \left(t\right) = 2 \cos t and y(t)=3sint. y \left(t\right) = 3 \sin t .

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Finding a Cartesian Equation Using Alternate Methods

Use two different methods to find the Cartesian equation equivalent to the given set of parametric equations.

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10.6 Exercise 14

Write the given parametric equations as a Cartesian equation: x(t)= t 3 x \left(t\right) = t^{3} and y(t)= t 6 . y \left(t\right) = t^{6} .

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10.6 Exercise 16

What is a system of parametric equations?

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10.6 Exercise 18

Explain how to eliminate a parameter given a set of parametric equations.

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10.6 Exercise 20

What is a benefit of using parametric equations?

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10.6 Exercise 22

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x( t )=5−t y( t )=8−2t \left\{\right. \begin{matrix}x \left(t\right) = 5 - t \\ y \left(t\right) = 8 - 2 t\end{matrix}

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10.6 Exercise 24

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x( t )=2t+1 y( t )=3 t \left\{\right. \begin{matrix}x \left(t\right) = 2 t + 1 \\ y \left(t\right) = 3 \sqrt{t}\end{matrix}

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10.6 Exercise 26

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x( t )=2 e t y( t )=1−5t \left\{\right. \begin{matrix}x \left(t\right) = 2 e^{t} \\ y \left(t\right) = 1 - 5 t\end{matrix}

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10.6 Exercise 28

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x(t)=4log(t) y(t)=3+2t \begin{cases} x \left(t\right) = 4 \text{log} \left(t\right) \\ y \left(t\right) = 3 + 2 t \end{cases}

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10.6 Exercise 30

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x( t )= t 3 −t y( t )=2t \left\{\right. \begin{matrix}x \left(t\right) = t^{3} - t \\ y \left(t\right) = 2 t\end{matrix}

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10.6 Exercise 32

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x( t )= e 2t y( t )= e 6t \left\{\right. \begin{matrix}x \left(t\right) = e^{2 t} \\ y \left(t\right) = e^{6 t}\end{matrix}

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10.6 Exercise 34

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x(t)=4cost y(t)=5sint \begin{cases} x \left(t\right) = 4 \text{cos} t \\ y \left(t\right) = 5 \sin t \end{cases}

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10.6 Exercise 36

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x(t)=2 cos 2 t y(t)=−sint \begin{cases} x \left(t\right) = 2 \text{cos}^{2} t \\ y \left(t\right) = - \sin t \end{cases}

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10.6 Exercise 38

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x(t)=t−1 y(t)= t 2 \begin{cases} x \left(t\right) = t - 1 \\ y \left(t\right) = t^{2} \end{cases}

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10.6 Exercise 40

Eliminate the parameter t t to rewrite the parametric equation as a Cartesian equation.

{ x(t)=2t−1 y(t)= t 3 −2 \begin{cases} x \left(t\right) = 2 t - 1 \\ y \left(t\right) = t^{3} - 2 \end{cases}

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10.6 Exercise 42

Rewrite the parametric equation as a Cartesian equation by building an x-y x - y table.

{ x(t)=4−t y(t)=3t+2 \begin{cases} x \left(t\right) = 4 - t \\ y \left(t\right) = 3 t + 2 \end{cases}

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10.6 Exercise 44

Rewrite the parametric equation as a Cartesian equation by building an x-y x - y table.

{ x(t)=4t−1 y(t)=4t+2 \begin{cases} x \left(t\right) = 4 t - 1 \\ y \left(t\right) = 4 t + 2 \end{cases}

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10.6 Exercise 46

Parameterize (write parametric equations for) each Cartesian equation by setting x( t )=t x \left(t\right) = t or by setting y(t)=t. y \left(t\right) = t .

y( x )=2sinx+1 y \left(x\right) = 2 \sin x + 1

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10.6 Exercise 48

Parameterize (write parametric equations for) each Cartesian equation by setting x( t )=t x \left(t\right) = t or by setting y(t)=t. y \left(t\right) = t .

x( y )= y +2y x \left(y\right) = \sqrt{y} + 2 y

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10.6 Exercise 50

Parameterize (write parametric equations for) each Cartesian equation by using x( t )=acost x \left(t\right) = a \cos t and y(t)=bsint. y \left(t\right) = b \sin t . Identify the curve.

x 2 16 + y 2 36 =1 \frac{x^{2}}{16} + \frac{y^{2}}{36} = 1

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10.6 Exercise 52

Parameterize (write parametric equations for) each Cartesian equation by using x( t )=acost x \left(t\right) = a \cos t and y(t)=bsint. y \left(t\right) = b \sin t . Identify the curve.

x 2 + y 2 =10 x^{2} + y^{2} = 10

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10.6 Exercise 54

Parameterize (write parametric equations for) each Cartesian equation by using x( t )=acost x \left(t\right) = a \cos t and y(t)=bsint. y \left(t\right) = b \sin t . Identify the curve.

Parameterize the line from (−1,0) \left(−1 , 0\right) to (3,−2) \left(3 , −2\right) so that the line is at (−1,0) \left(−1 , 0\right) at t=0, t = 0 , and at (3,−2) \left(3 , −2\right) at t=1. t = 1.

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10.6 Exercise 56

Parameterize (write parametric equations for) each Cartesian equation by using x( t )=acost x \left(t\right) = a \cos t and y(t)=bsint. y \left(t\right) = b \sin t . Identify the curve.

Parameterize the line from (4,1) \left(4 , 1\right) to (6,−2) \left(6 , −2\right) so that the line is at (4,1) \left(4 , 1\right) at t=0, t = 0 , and at (6,−2) \left(6 , −2\right) at t=1. t = 1.

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10.6 Exercise 58

Use the table feature in the graphing calculator to determine whether the graphs intersect.

{ x 1 (t)= t 2 y 1 (t)=2t−1  and { x 2 (t)=−t+6 y 2 (t)=t+1 \left\{\right. \begin{matrix}x_{1} \left(t\right) = t^{2} \\ y_{1} \left(t\right) = 2 t - 1\end{matrix} \textrm{ }\text{and}\textrm{ } \left\{\right. \begin{matrix}x_{2} \left(t\right) = - t + 6 \\ y_{2} \left(t\right) = t + 1\end{matrix}

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10.6 Exercise 60

Use a graphing calculator to complete the table of values for each set of parametric equations.

{ x 1 ( t )= t 2 −4 y 1 ( t )=2 t 2 −1 \left\{\right. \begin{matrix}x_{1} \left(t\right) = t^{2} - 4 \\ y_{1} \left(t\right) = 2 t^{2} - 1\end{matrix}

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10.6 Exercise 62

Find two different sets of parametric equations for y= ( x+1 ) 2 . y = \left(x + 1\right)^{2} .

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10.6 Exercise 64

Find two different sets of parametric equations for y= x 2 −4x+4. y = x^{2} - 4 x + 4.

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Adapted from College Algebra © 2021 Rice University. Licensed under CC BY 4.0. Sources: College Algebra 2e, Algebra and Trigonometry 2e, Precalculus 2e, College Algebra with Corequisite Support 2e. Imported at revision 4922e46.