An ellipse has a center at the origin, a vertex along the major axis at \((13,0)\), and a focus at \((12,0)\). What is the equation of the ellipse?

A. \(\frac{x^2}{13^2} + \frac{y^2}{12^2} = 1\)

B. \(\frac{y^2}{13^2} + \frac{x^2}{12^2} = 1\)

C. \(\frac{x^2}{13^2} + \frac{y^2}{5^2} = 1\)

D. [tex]\(\frac{y^2}{13^2} + \frac{x^2}{5^2} = 1\)[/tex]



Answer :

To determine the equation of the ellipse, let's follow the necessary steps:

1. Identify the Values:
- The center of the ellipse is at the origin \((0,0)\).
- The vertex along the major axis is at \((13,0)\). This means the semi-major axis length \(a\) is 13.
- The focus is at \((12,0)\), giving us the distance from the center to the focus, \(c\), which is 12.

2. Relationship Between \(a\), \(b\), and \(c\):
- In an ellipse, the relationship between the semi-major axis \(a\), the semi-minor axis \(b\), and the distance to the focus \(c\) is given by the equation:
[tex]\[ c^2 = a^2 - b^2 \][/tex]

3. Calculate \(a^2\) and \(c^2\):
- Given \(a = 13\):
[tex]\[ a^2 = 13^2 = 169 \][/tex]
- Given \(c = 12\):
[tex]\[ c^2 = 12^2 = 144 \][/tex]

4. Solve for \(b^2\):
- Using the relationship \(c^2 = a^2 - b^2\):
[tex]\[ 144 = 169 - b^2 \][/tex]
- Rearrange to solve for \(b^2\):
[tex]\[ b^2 = 169 - 144 = 25 \][/tex]

5. Equation of the Ellipse:
- The standard form of the equation of an ellipse centered at the origin is:
[tex]\[ \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \][/tex]
- Substitute the values \(a^2 = 169\) and \(b^2 = 25\):
[tex]\[ \frac{x^2}{13^2} + \frac{y^2}{5^2} = 1 \][/tex]

This matches the third option provided in the question. Therefore, the equation of the ellipse is:

[tex]\[ \boxed{\frac{x^2}{13^2} + \frac{y^2}{5^2} = 1} \][/tex]

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