GeoGebra Classroom 2.2
2.2.1 - The medians share a point of concurrency
2.2.2 - The ratio is always 2
2.2.10 - The subtriangles are congruent iff the triangle is equilateral
2.3.1 - The altitudes are always concurrent (at the orthocenter)
2.3.2 - Orthocenter and Centroid
2.3.3 - Orthocenter is outside the triangle if the triangle is obtuse
2.3.4 - Centroid and Orthocenter are at the same point if the triangle is equilateral
2.4.1, 2.4.2, 2.4.3, 2.4.5 - Circumcenter and Centroid at the same point if the triangle is equilateral
2.5.1, 2.5.2 - The Euler Lines
2.5.5 - Figure 2.4 with an arbitrary triangle
2.5.8 - Isosceles triangle, internal angle bisectors congruent