# Conics - Semi Major/Minor Axis

1. May 17, 2007

### katrina007

Hi,

I have this homework question and I completed and found the the foci and the center for the ellipse, but I dont understand how to find the semi major and minor axis.

Graph and give the center, semi major and semi minor axis and foci of the ellipse

25x^2 + 350x + 9y^2 - 54y +1081 = 0

For the center and Foci I got:
Center: [7, 3]
Foci: [11, 3] & [3, 3]

If anyone can help me with this, that'd be appreciated. Thanks in advance.
- Katrina

2. May 17, 2007

### NateTG

The major axis is the line that joins the foci.
The minor axis is the line that goes through the center of the ellipse, and is perpendicular to the major axis.

3. May 17, 2007

### katrina007

i still dont know what the means or how to figure out the axis....can someone plz tell me the axis and how they got it? do i need to use formula or something?

4. May 17, 2007

### Dick

How did you find the center and foci? If you did the usual complete the squares routine then the axis lengths can be read off from that.

5. May 18, 2007

### katrina007

yes i did that...but what do i read to tell the major/minor axes?

6. May 18, 2007

### hage567

So if you have it in the form
$$\frac{(x-h)^2}{a^2}+\frac{(y-k)^2}{b^2}=1$$
a and b are what you need to look at.

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