There are many notions of the center of a triangle. TriangleConstruct can compute these different centers as well as related lines.
Construct the orthocenter of the triangle tri.
Construct the three altitudes of the triangle.
The orthocenter is the intersection of the three altitudes of the triangle.
Visualize the orthocenter and the three altitudes.
Compute additional centers.
A symmedian of a triangle is the reflection of a median across its corresponding angle bisector. The three symmedians intersect at a center called the symmedian point.
Visualize these three centers as well as their corresponding lines and circles. The centroid is the intersection of the three medians, and the incenter is both the center of the inscribed circle and the intersection of the angle bisectors.