Geometry

Interactive Practice

See an explanation or a demonstration

Interact with a theorem!

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Title Description
Euclid's Elements
This site contains the entire contents of Euclid's Elements and with each proposition is a diagram you can manipulate in order to help you understand the proposition.
Pythagorean Theorem
Jim Morey created this elegant interactive geometric proof of the Pythagorean Theorem.
Formula for the area of a circle
Animation showing why the formula for the area of a circle is what it is, based on a diagram in Steven Strogatz's column Take It to the Limit. This approach also provides an approximation for π.