This is the first example in the file Geogebra quickstart provided by the author.
The icon on the right links to this construction in an applet.
The task is to construct the circumcircle of a given triangle.
Step 1 Make a triangle
Step 2 Construct perpendicular bisectors
Step 3 Get the intersection
Step 4 Construct the circumcircle
Step 5 Alter the triangle
Get the original quickstart file to see more tips about this construction by the author.