4. An ellipse has a vertex at [tex]$(3,0)$[/tex], a co-vertex at [tex]$(0,-1)$[/tex], and a center at the origin. Which is the equation of the ellipse?

A. [tex]$\frac{x^2}{9}+\frac{y^2}{1}=1$[/tex]
B. [tex]$\frac{x^2}{9}+\frac{y^2}{3}=1$[/tex]
C. [tex]$\frac{x^2}{3}+\frac{y^2}{1}=1$[/tex]
D. [tex]$\frac{x^2}{1}+\frac{y^2}{9}=1$[/tex]



Answer :

To determine the equation of the ellipse, we need to utilize the information given:

1. Vertices and Co-vertices:
- The vertex is at [tex]\((3, 0)\)[/tex].
- The co-vertex is at [tex]\((0, -1)\)[/tex].

2. Center:
- The center is at the origin [tex]\((0, 0)\)[/tex].

Using this information, we'll identify the parameters of the ellipse:

### Step 1: Identify the distances [tex]\(a\)[/tex] and [tex]\(b\)[/tex]
- Distance from the center to the vertex at (3, 0): This distance is referred to as [tex]\(a\)[/tex], which represents the semi-major axis.
[tex]\[ a = 3 \][/tex]

- Distance from the center to the co-vertex at (0, -1): This distance is referred to as [tex]\(b\)[/tex], which represents the semi-minor axis.
[tex]\[ b = 1 \][/tex]

### Step 2: Form the equation of the ellipse
The standard form of the equation of an ellipse with the major axis along the x-axis and centered at the origin is:
[tex]\[ \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \][/tex]

### Step 3: Substitute [tex]\(a\)[/tex] and [tex]\(b\)[/tex] into the equation
- [tex]\(a = 3\)[/tex], so [tex]\(a^2 = 3^2 = 9\)[/tex]
- [tex]\(b = 1\)[/tex], so [tex]\(b^2 = 1^2 = 1\)[/tex]

Substitute these values into the standard form equation:
[tex]\[ \frac{x^2}{9} + \frac{y^2}{1} = 1 \][/tex]

### Step 4: Simplify the equation
[tex]\[ \frac{x^2}{9} + y^2 = 1 \][/tex]

Thus, the correct equation of the ellipse is:

[tex]\[ \boxed{\frac{x^2}{9} + y^2 = 1} \][/tex]