5 Orthocenter Things That Geometry Kids Should Know

The Orthocenter cuts each altitude into two parts whose products for each altitude are equal.
[size=200]AH x HF = CH x HD = BH x HE[/size]
Distance from Orthocenter to Vertex, Length of Opposite Side, Circumcircle Diameter
[size=200]AH[sup]2[/sup] + BC[sup]2[/sup] = BH[sup]2 [/sup]+ AC[sup]2[/sup] = CH[sup]2 [/sup]+ AB[sup]2[/sup] = Diameter[sup]2[/sup] [br][/size]
Distances from the Orthocenter to the Vertices.
[size=200]AH + BH + CH = Incircle Diameter + Circumcircle Diameter[/size]
Distances from the Orthocenter to the Vertices 2
[size=200]Distance from Orthocenter to Vertex = 2 x Distance from Circumcenter to opposite side[/size]
Orthocentric Quartet
[size=200]Given 3 points and their Orthocenter, any of the 4 points is the Orthocenter of the other 3 points.[/size]
– Steve Phelps

Information: 5 Orthocenter Things That Geometry Kids Should Know