Q:

# How do you find the foci of an ellipse?

A:

To find the foci of an ellipse, find the center of the ellipse, and determine the distance from the center to the farthest point and the closest point on the boundary. Then, use the formula F = square root of "x" squared minus "y" squared.

## Keep Learning

1. Find the center

Determine the distance between the farthest two opposing points on the ellipse, and divide by 2. Then, do the same for the two opposing points that have the shortest distance. This gives the center point.

2. Finding variables

Assign "x" to the value of the longest distance divided by 2, or the distance from the center to the farthest point on the boundary, and "y" to the shortest distance divided by 2, or the distance from the center to the closest point on the boundary.

3. Using the formula

Plug in "x" and "y" found in the previous step into the formula. Square both "x" and "y." Then, subtract "y" squared from "x" squared. Take the square root of the result. This gives "F," which is the distance of the foci from the center.

4. Applying formula to the ellipse

The foci lies on the line that goes through the center to both of the farthest points from the center. Starting from the center, follow the line to the farthest points. The foci is "F" distance away from the center in both directions.

Sources:

## Related Questions

• A: A circle is actually a special kind of ellipse where the two focuses are equal. Every ellipse contains two points called a focus. The perimeter of the elli... Full Answer >
Filed Under:
• A: To draw an ellipse or oval with a string, a person needs to pinpoint the exact measurements with a compass and pins, and move a pencil in an arc after it h... Full Answer >
Filed Under:
• A: To calculate the area of an ellipse, multiply the major radius by the minor radius, then multiply by pi. For simplicity, use a commonly accepted approximat... Full Answer >
Filed Under:
• A: The center of a circle is simply referred to as the center. However, it is often given the distinction of "0" in drawings and formulas of circles. The cent... Full Answer >
Filed Under:
PEOPLE SEARCH FOR