Geometer's Sketchpad Unit Circle
Requires Geometer's Sketchpad
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Graphs of Sine and Cosine (QuickTime)

Animation: Values of Tangent
Requires Geometer's Sketchpad
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Conic Sections Defined by Eccentricity
1. Move the slider for eccentricity and see what kind of conic section you get.
2. Move the focus to see what impact that has on the figure.
3. Move a point on the directrix to show that no matter what point is taken on the curve, the ratio of the distance to the focus over the distance to the directrix always equals the eccentricity.

How to Find Volumes by Parallel Cross-Sections

Parallel Cross-Section Figures

Morphing Quadric Surfaces
Move coefficient sliders
Graphing Calculator version

Tautochrone--sliding
beads on a cycloid
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The Quicktime version is a movie clip.
The Graphing Calculator version is interactive. It requires a free viewer, which is available here for both PC and Mac platforms.