Google Classroom
GeoGebraGeoGebra Classroom

Nine Point Circle

This is the nine point circle. The nine point circle is a circle which appears in any triangle, made up of midpoints and intersections of perpendicular lines that cross through points. Instructions for its creation are here, and simplified here. The black lines are construction of the points, the orange lines are construction of the circle's centre. Drag the dots A, B, C to change the size and shape of the triangle.
  1. Find the relation between the positions of the lines and dots and the type of triangle (e.g. right-angled, equilateral, isosceles)
  2. Construct the nine point triangle using the instructions here.