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ERIC Number: EJ877234
Record Type: Journal
Publication Date: 2010-Mar
Pages: 7
Abstractor: As Provided
Reference Count: 0
ISSN: ISSN-0746-8342
The Dance of the Foci
Seppala-Holtzman, David
College Mathematics Journal, v41 n2 p122-128 Mar 2010
It's well known that slicing a cone with a plane and then allowing the plane to rotate through all possible angles of inclination yields the conic sections. What paths then do the foci of these conics trace out as this cutting plane passes through the different angles? In this article, we derive formulae for these trajectories and generate the associated curves. Of particular interest is how they articulate when the conic shifts from ellipse to parabola to hyperbola.
Mathematical Association of America. 1529 Eighteenth Street NW, Washington, DC 20036. Tel: 800-741-9415; Tel: 202-387-5200; Fax: 202-387-1208; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A