Concurrent Circles and Minimum Triangle
James Tanton tweeted a nice problem: how to arrange three concurrent congruent circles so that the smallest triangle containing them has the least area.
More GeoGebra at
Exploring polygons formed by midpoints of sides of 3, 4, 6-gon
Introduction to straight line graphs
Incenter and Excenters
Mathematics Fundamentals II
The Reduced Row Echelon Form of a Matrix
Langford's Problem, Roy O. Davies Construction
InCenter and ExCenter
Random Walks in the Plane
A strange way to generate an ellipse?
Exploding Dots (Overview)!
Tanton's Triangle Problem (Revised Draft)