# Collinearity of an Orthocenter, the Incenter, and the Circumcenter

Requires a Wolfram Notebook System

Interact on desktop, mobile and cloud with the free Wolfram CDF Player or other Wolfram Language products.

Requires a Wolfram Notebook System

Edit on desktop, mobile and cloud with any Wolfram Language product.

Let ABC be a triangle with incenter I and circumcenter O. Let the incircle intersect AB, BC, and CA at M, N, and P, respectively. Let the orthocenter (the intersection of the altitudes) of MNP be H. Then H, I, and O are collinear.

Contributed by: Jay Warendorff (March 2011)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

See Example 6 on page 4 of Mathematical Excalibur, Volume 9, No. 2.