As stated previuosly, the orthocenter (H), cicumcenter (C), and centroid (G), are all collinear. The line the contains the three centers of a triangle is called the Euler line. Click here to open a GSP construction of a Euler line so that you can manipulate the line.

Notice that the Euler line can extend beyond the sides of the triangle as depicted below. To see a script of the GSP construction of the Euler line, click here.