Hyperbola by Foci - Cinderella Documentation
Description: The user's guide to the Interactive Geometry Software Cinderella

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# Hyperbola by Foci

This mode constructs a hyperbola defined by two foci and one perimeter point. After selecting the mode one has to click the first focus point, the second focus point, and a perimeter point in this order.

#### Synopsis

A hyperbola is constructed from two foci and a perimeter point.

#### Caution

Due to the continuity behavior of Cinderella it may happen that while free elements are being moved, a hyperbola transforms continuously into a ellipse. This may happen if one of the foci passes through infinity.

#### See Also

- Ellipse by Foci
- Parabola by Focus and Directrix