You can link directly to my content on GeoGebra here.

Sample of GeoGebra Applets
Regular Polygons and Area
Area of Inscribed Regular Polygons and Circles
Segment Addition Postulate
Measure and Classification of Angles

Applet demonstrating the centers of triangles

Acknowledgement: This work was supported by a 2015 Faculty Innovator Grant through Old Dominion University’s Center for Learning and Teaching.