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Interactive
University of St. Andrews (UK)

University of St. Andrews: Cissoid of Diocles

For Students 9th - 10th
Detailed and comprehensive site explaining the Cissoid of Diocles. A Java-enhanced interactive is included.
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Handout
Wolfram Research

Wolfram Math World: Cissoid of Diocles Pedal Curve

For Students 9th - 10th
Short site explaining the Cissoid of Diocles Pedal Curve. The site has links to related topics, and includes a graph and a brief explanation.