An ellipse has a center at the origin, a vertex along the major axis at [tex]\((0, 17)\)[/tex], and a focus at [tex]\((0, -8)\)[/tex].

Which equation represents this ellipse?

A. [tex]\(\frac{x^2}{17^2} + \frac{y^2}{8^2} = 1\)[/tex]

B. [tex]\(\frac{x^2}{17^2} + \frac{y^2}{15^2} = 1\)[/tex]

C. [tex]\(\frac{y^2}{17^2} + \frac{x^2}{8^2} = 1\)[/tex]

D. [tex]\(\frac{y^2}{17^2} + \frac{x^2}{15^2} = 1\)[/tex]



Answer :

Let's determine the correct equation for an ellipse centered at the origin, with one vertex at [tex]\((0, 17)\)[/tex] and one focus at [tex]\((0, -8)\)[/tex].

1. Identifying the major axis:

Since the vertex [tex]\((0, 17)\)[/tex] lies on the y-axis, we know this is a vertically oriented ellipse. In such an ellipse, the equation takes the form:

[tex]\[ \frac{y^2}{a^2} + \frac{x^2}{b^2} = 1 \][/tex]

Here, [tex]\(a\)[/tex] is the distance from the center to a vertex, and [tex]\(b\)[/tex] is the distance from the center to a co-vertex.

2. Determining [tex]\(a\)[/tex], the semi-major axis length:

For the given vertex at [tex]\((0, 17)\)[/tex], [tex]\(a = 17\)[/tex].

3. Determining [tex]\(c\)[/tex], the focal distance:

The focus is at [tex]\((0, -8)\)[/tex], so [tex]\(c = 8\)[/tex].

4. Relationship between [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex]:

For an ellipse, the relationship between [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] is given by:

[tex]\[ a^2 = b^2 + c^2 \][/tex]

Using the given values, we get:

[tex]\[ 17^2 = b^2 + 8^2 \][/tex]

[tex]\[ 289 = b^2 + 64 \][/tex]

[tex]\[ b^2 = 289 - 64 \][/tex]

[tex]\[ b^2 = 225 \][/tex]

[tex]\[ b = \sqrt{225} \][/tex]

[tex]\[ b = 15 \][/tex]

5. Forming the equation of the ellipse:

Incorporating the values of [tex]\(a\)[/tex] and [tex]\(b\)[/tex] into the standard form of the ellipse's equation, we get:

[tex]\[ \frac{y^2}{17^2} + \frac{x^2}{15^2} = 1 \][/tex]

Thus, the correct equation representing the given ellipse is:

[tex]\[ \frac{y^2}{17^2} + \frac{x^2}{15^2} = 1 \][/tex]

Therefore, the correct answer is:

[tex]\[ \boxed{\frac{y^2}{17^2}+\frac{x^2}{15^2}=1} \][/tex]