Math Problem Statement

Given the following parametric equations, eliminate the parameter, tt​, and rewrite the parametric equations as a Cartesian equation. 

x(t)=−3sin⁡(t)y(t)=2cos⁡(t)x(t)y(t)​=−3sin(t)=2cos(t)​​where 0≤t≤2π0≤t≤2π​​. 

Solution

To eliminate the parameter tt from the given parametric equations and rewrite them as a Cartesian equation, we can use trigonometric identities. The given parametric equations are:

x(t)=3sin(t)x(t) = -3 \sin(t) y(t)=2cos(t)y(t) = 2 \cos(t)

We start by isolating the trigonometric functions in terms of xx and yy:

  1. From x(t)=3sin(t)x(t) = -3 \sin(t): sin(t)=x3\sin(t) = -\frac{x}{3}

  2. From y(t)=2cos(t)y(t) = 2 \cos(t): cos(t)=y2\cos(t) = \frac{y}{2}

Next, we use the Pythagorean identity for sine and cosine, which states: sin2(t)+cos2(t)=1\sin^2(t) + \cos^2(t) = 1

Substituting the expressions for sin(t)\sin(t) and cos(t)\cos(t) into this identity, we get: (x3)2+(y2)2=1\left(-\frac{x}{3}\right)^2 + \left(\frac{y}{2}\right)^2 = 1

Simplifying this, we obtain: x29+y24=1\frac{x^2}{9} + \frac{y^2}{4} = 1

This is the equation of an ellipse in Cartesian coordinates. Thus, the parametric equations x(t)=3sin(t)x(t) = -3 \sin(t) and y(t)=2cos(t)y(t) = 2 \cos(t) can be rewritten as the Cartesian equation: x29+y24=1\frac{x^2}{9} + \frac{y^2}{4} = 1

If you have any questions or need further details, please let me know.

Here are 5 related questions for further practice:

  1. What is the parametric form of the ellipse x216+y225=1\frac{x^2}{16} + \frac{y^2}{25} = 1?
  2. How would you convert the parametric equations x(t)=5cos(t)x(t) = 5 \cos(t) and y(t)=7sin(t)y(t) = 7 \sin(t) to Cartesian form?
  3. What are the major and minor axes of the ellipse described by x236+y249=1\frac{x^2}{36} + \frac{y^2}{49} = 1?
  4. If the parametric equations are given by x(t)=4cos(t)x(t) = 4 \cos(t) and y(t)=3sin(t)y(t) = 3 \sin(t), what is the range of tt to complete one full cycle of the ellipse?
  5. How can you determine the orientation of an ellipse given its parametric equations?

Tip: When converting parametric equations to Cartesian form, always look for trigonometric identities or algebraic relationships that can help eliminate the parameter.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Parametric Equations
Cartesian Equations
Ellipses

Formulas

x(t) = -3sin(t)
y(t) = 2cos(t)
Pythagorean identity: sin²(t) + cos²(t) = 1
Equation of an ellipse: x²/a² + y²/b² = 1

Theorems

Pythagorean Identity

Suitable Grade Level

Grades 10-12