Significant Nine Points
The diagram above shows the nine significant points of the nine-point circle. Points D, E, and F are the midpoints of the three sides of the triangle. Points G, H, and I are the feet of the altitudes of the triangle. Points J, K, and L are the midpoints of the line segments between each altitude's vertex intersection (points A, B, and C) and the triangle's orthocenter (point S).
For an acute triangle, six of the points (the midpoints and altitude feet) lie on the triangle itself; for an obtuse triangle two of the altitudes have feet outside the triangle, but these feet still belong to the nine-point circle.
Read more about this topic: Nine-point Circle
Famous quotes containing the words significant and/or points:
“Never is a historic deed already completed when it is done but always only when it is handed down to posterity. What we call “history” by no means represents the sum total of all significant deeds.... World history ... only comprises that tiny lighted sector which chanced to be placed in the spotlight by poetic or scholarly depictions.”
—Stefan Zweig (18811942)
“The dominant metaphor of conceptual relativism, that of differing points of view, seems to betray an underlying paradox. Different points of view make sense, but only if there is a common co-ordinate system on which to plot them; yet the existence of a common system belies the claim of dramatic incomparability.”
—Donald Davidson (b. 1917)