Math Problem Statement

Curve C is set by x(t)=3sin(4t) and y(t)=5cos(4t) for 0<= t <=2pi. Write the equation jn terms of x and y and graph it

Solution

To eliminate the parameter tt from the parametric equations x(t)=3sin(4t)x(t) = 3\sin(4t) and y(t)=5cos(4t)y(t) = 5\cos(4t), we use the trigonometric identity sin2θ+cos2θ=1\sin^2\theta + \cos^2\theta = 1.

Step 1: Solve for sin(4t)\sin(4t) and cos(4t)\cos(4t) in terms of xx and yy

From x(t)=3sin(4t)x(t) = 3\sin(4t): sin(4t)=x3.\sin(4t) = \frac{x}{3}.

From y(t)=5cos(4t)y(t) = 5\cos(4t): cos(4t)=y5.\cos(4t) = \frac{y}{5}.

Step 2: Apply the Pythagorean identity

sin2(4t)+cos2(4t)=1.\sin^2(4t) + \cos^2(4t) = 1.

Substitute sin(4t)=x3\sin(4t) = \frac{x}{3} and cos(4t)=y5\cos(4t) = \frac{y}{5}: (x3)2+(y5)2=1.\left(\frac{x}{3}\right)^2 + \left(\frac{y}{5}\right)^2 = 1.

Step 3: Simplify the equation

x29+y225=1.\frac{x^2}{9} + \frac{y^2}{25} = 1.

This is the equation of an ellipse with:

  • Semi-major axis a=5a = 5 along the yy-axis.
  • Semi-minor axis b=3b = 3 along the xx-axis.

Step 4: Graph the ellipse

Let me plot the ellipse based on the equation x29+y225=1\frac{x^2}{9} + \frac{y^2}{25} = 1. numpy as np import matplotlib.pyplot as plt

Define the parameters for the ellipse

a = 5 # Semi-major axis (y-direction) b = 3 # Semi-minor axis (x-direction)

Parametric angle

t = np.linspace(0, 2 * np.pi, 500)

Ellipse points

x = b * np.cos(t) y = a * np.sin(t)

Plot the ellipse

plt.figure(figsize=(8, 8)) plt.plot(x, y, label=r'$\frac{x^2}{9} + \frac{y^2}{25} = 1$', color='blue') plt.axhline(0, color='black',linewidth=0.5, linestyle='--') plt.axvline(0, color='black',linewidth=0.5, linestyle='--') plt.gca().set_aspect('equal', adjustable='box') plt.title('Graph of the Ellipse', fontsize=14) plt.xlabel('x', fontsize=12) plt.ylabel('y', fontsize=12) plt.legend(fontsize=12) plt.grid(True) plt.show()Here is the graph of the ellipse defined by the equation x29+y225=1\frac{x^2}{9} + \frac{y^2}{25} = 1. The semi-major axis extends along the yy-axis, and the semi-minor axis extends along the xx-axis.

Would you like further details on any aspect of this solution or its derivation?

Here are 5 related questions for further exploration:

  1. What are the foci of this ellipse, and how can they be calculated?
  2. How do we parameterize a rotated ellipse in terms of tt?
  3. What is the area enclosed by this ellipse?
  4. How does the equation of the ellipse change if it is translated from the origin?
  5. Can this ellipse be described in polar coordinates? How?

Tip: For any ellipse, the sum of the distances from any point on the ellipse to the two foci is always constant.

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Math Problem Analysis

Mathematical Concepts

Parametric Equations
Ellipses
Trigonometric Identities

Formulas

sin^2(θ) + cos^2(θ) = 1
x(t) = 3sin(4t)
y(t) = 5cos(4t)
x^2 / 9 + y^2 / 25 = 1

Theorems

Pythagorean Identity
Equation of an Ellipse

Suitable Grade Level

Grades 9-12