Some interesting Math facts...

1. If you join together the feet of the altitudes of a triangle, they make another triangle called the pedal triangle, and the orthocentre is the incentre of this pedal triangle.

2. The orthocentre, circumcentre and centroid are collinear (Euler’s line) and the centroid is two thirds the distance from the orthocenter to the circumcenter. The incenter is not on the Euler line except when the triangle is isosceles. When the triangle is isosceles, the Euler Line also passes through one of the vertices!

3. Take a triangle with vertices at A, B and C, and let H be its orthocenter. The orthocenter for any of the triangles formed from three of these four points is the fourth point. (4 points which satisfy this condition are called an orthocentric set.)

4. The distance from the orthocenter to a vertex is twice the distance from the circumcenter to the opposite side of the vertex.

One great math site that I love to visit frequently is www.mathforum.org and it is rich with all the knowledge that you will ever need!