Finding the foci of a given ellipse
Geometry construction using a compass and straightedge
This shows how to find the two
given its width and height
(major and minor axes).
This can be used to find the two focus points when you are planning to draw an ellipse using the
string and pins method.
Uses a compass, no measuring is used. A Euclidean construction.
Printable step-by-step instructions
The above animation is available as a
printable step-by-step instruction sheet, which can be used for making handouts
or when a computer is not available.
Try it yourself
Click here for a printable worksheet containing an ellipse drawing problem.
When you get to the page, use the browser print command to print as many as you wish. The printed output is not copyright.
Constructions pages on this site
Circles, Arcs and Ellipses
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