Explanation

An ellipse looks like a stretched circle.

Standard form (center at origin):
x²/a² + y²/b² = 1

Where:

• Center = (0, 0)

• a = radius in the x-direction (semi-major axis)

• b = radius in the y-direction (semi-minor axis)

If a > b:

• Major axis is horizontal

If b > a:

• Major axis is vertical

Shifted ellipse:
(x − h)²/a² + (y − k)²/b² = 1
Center = (h, k)

Quiz

1. What point is the center of x²/9 + y²/4 = 1?

2. What are the radii of the ellipse?

3. Which axis is longer if a > b?

4. What does a represent?

5. Does an ellipse have one or two radii?

Answer Key

1. (0, 0)

2. a = 3, b = 2

3. Horizontal

4. Semi-major axis

5. Two