Math Problem Statement

Foci at (±2,0) and vertex at (−7 /2 ,0)

Solution

Given the foci and vertex of the ellipse, we can determine its standard form. Here's how:

Step 1: Identify the coordinates of the foci and the vertex

  • Foci: (±2,0)(\pm 2, 0) which means the foci are at (2,0)(2, 0) and (2,0)(-2, 0).
  • Vertex: (72,0)\left(-\frac{7}{2}, 0\right).

Step 2: Determine the center of the ellipse

Since the foci are symmetric around the origin and lie on the xx-axis, the center of the ellipse is at the origin (0,0)(0, 0).

Step 3: Determine the distance from the center to the foci (cc)

The distance cc from the center to either focus is: c=2c = 2

Step 4: Determine the distance from the center to the vertex (aa)

The distance aa from the center to the vertex (72,0)\left(-\frac{7}{2}, 0\right) is: a=0(72)=72=3.5a = \left|0 - \left(-\frac{7}{2}\right)\right| = \frac{7}{2} = 3.5

Step 5: Calculate bb (semi-minor axis)

The relationship between aa, bb, and cc for an ellipse is given by: c2=a2b2c^2 = a^2 - b^2 Substituting the known values: 22=(72)2b22^2 = \left(\frac{7}{2}\right)^2 - b^2 4=494b24 = \frac{49}{4} - b^2 b2=494164=334b^2 = \frac{49}{4} - \frac{16}{4} = \frac{33}{4} b=332b = \frac{\sqrt{33}}{2}

Step 6: Write the equation of the ellipse

Since the major axis is horizontal (along the xx-axis), the standard form of the ellipse is: x2a2+y2b2=1\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 Substituting a2=(72)2=494a^2 = \left(\frac{7}{2}\right)^2 = \frac{49}{4} and b2=334b^2 = \frac{33}{4}, the equation becomes: x2494+y2334=1\frac{x^2}{\frac{49}{4}} + \frac{y^2}{\frac{33}{4}} = 1 This simplifies to: 4x249+4y233=1\frac{4x^2}{49} + \frac{4y^2}{33} = 1

This is the standard form of the ellipse.

Would you like more details or have any questions?

Here are five related questions for further exploration:

  1. How do you determine the center of an ellipse if the foci are not at the origin?
  2. What happens to the shape of an ellipse as the distance between the foci increases?
  3. How can you find the equation of an ellipse if you only know the length of the major and minor axes?
  4. How does the equation of an ellipse change if the major axis is vertical instead of horizontal?
  5. What is the geometric significance of the semi-minor axis in an ellipse?

Tip: When dealing with ellipses, always check whether the major axis is horizontal or vertical to use the correct form of the equation.

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Math Problem Analysis

Mathematical Concepts

Geometry
Conic Sections
Ellipses

Formulas

Standard form of ellipse

Theorems

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Suitable Grade Level

Grades 11-12