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Your Notes<br />
Homework<br />
Example 3 Write an equation given a vertex and a focus<br />
Write an equation of the ellipse that has a vertex at<br />
(26, 0) and a focus at (5, 0).<br />
Solution<br />
Make a sketch of the ellipse.<br />
Because the vertex and focus lie<br />
on the , the major axis is<br />
, with a 5 and<br />
c 5 . To find b, use the equation<br />
c 2 5 a 2 2 b 2 .<br />
5 2 b 2<br />
b 2 5 2 5<br />
b 5<br />
An equation is 5 1, or 5 1.<br />
Checkpoint Graph the equation. Identify the vertices,<br />
co-vertices, and foci of the ellipse.<br />
1. x2 1 y2<br />
} 5 1<br />
25<br />
Checkpoint Write an equation of the ellipse with the<br />
given characteristics and center at (0, 0).<br />
2. Vertex: (29, 0) 3. Vertex: (0, 7)<br />
Co-vertex: (0, 4) Focus: (0, 23)<br />
Copyright © Holt McDougal. All rights reserved. Lesson 9.4 Algebra 2 Notetaking Guide 243<br />
2<br />
2<br />
y<br />
y<br />
2<br />
2<br />
x<br />
x