The nine point circle
- Zoltán Kovács
The nine-point circle can be constructed for any given triangle. It passes through nine significant concyclic points defined from the triangle. Those are: the midpoint of each side of the triangle, the foot of each altitude and the midpoint of the line segment from each vertex of the triangle to the orthocenter.
- Select the Relation Tool (from the 10th toolbox) and check if the concyclic points indeed lie on the circle. Click "More" to start a symbolic check.
- You may also check that points D and K are not generally coincide.