# GeoGebra

is a dynamic mathematics software that joins geometry, algebra and calculus. It is developed for education in secondary schools by Markus Hohenwarter at the University of Salzburg. Click here to visit the official homepage. This freeware program uses Java, and runs on almost any modern platform. GeoGebra received several international awards including the European and German educational software awards.

**Area:**Investigate how the area formulas of polygons are developed and how the are related to each other. Some of the pages were adapted from Manuel Sada’s Spanish language mathematics web site.**Polygons:**Investigate the sums of the interior and exteriors angles of polygons.**Pythagorean Thm.:**Take a look a four visual proofs of this famous theorem. Try your hand solving a puzzle based on a proof. There is also a problem to solve.**Transformations:**Explore translations, reflections, and rotations.**Other:**Use an on-line protractor to measure angles. Investigate a median of a right triangles. Explore Triangle Side Inequalities with this interactive page.