An ellipse has a center at the origin, a vertex along the major axis at (20, 0), and a focus at (16, 0). the equation of the ellipse is in the form below. what is the value of b in the equation? (enter a positive number.)b =

If the center is at (0, 0) and the vertex is at (20, 0), then the distance, a, is the length from the center to the vertex, 20.  The distance from the center to the focus is c.  The distance from the center to the focus is 16, so c = 16.  The formula we use to find the focus is .  We have our c value and our a value, so we will sub in those to find b.  and 256 = 400 - b^2.  -b^2 = -144, so b = 12.  There you go!