The nine-point-circle
Geometry
Level
5
For a triangle with sides 13, 15 and altitude 12, find the radius of the circle that passes through the following points:
- the midpoint of each side,
- the foot of each altitude, and
- the midpoint of the line segment from each vertex to the orthocenter.
If the radius can be written as \(a + \frac{m}{n}\), where \(a,m,\) and \(n\) are positive integers, \(m<n,\) and \(m\) and \(n\) are coprime, find \(a+m+n\).
Note: Assume the given altitude to be through the vertex common to both the given sides.
by
Digvijay Singh