Triangle/Nine-point circle/Fact
< Triangle < Nine-point circle
Theorem about the Nine-point circle
Let a nondegenerate triangle in the Euclidean plane with vertices be given. Let be the circumcircle of the midpoints of the sides of the triangle. Then the following statements hold.
- The radius of is half of the radius of the circumcircle of .
- The line segements between the orthocenter and the vertices are cut in halves by .
- The feet of the altitudes of lie on .