Ellipses

Example 1

Graph the following ellipse. Find its vertices, length of the major axis, co-vertices, length of the minor axis, and foci.

ellipses_ex1-1

Step 1 . Identify the vertices and length of major axis.

Since the larger denominator is with the y variable, the major axis lies along the y-axis. Since a2 = 9, |a| = 3.

Vertices: (0, 3), (0, -3)

Length of major axis: 6

Step 2. Identify the co-vertices and length of minor axis.

Since the smaller denominator is with the x variable, the minor axis lies along the x-axis. Since b2 = 4, |b| = 2.

Co-vertices: (2, 0), (-2, 0)

Length of minor axis: 4

Step 3. Identify the foci.

ellipses_ex1-2

Step 4. Graph the ellipse.

ellipses_ex1-3