Proof Without Words
Drag the points in the sketch below. What do you notice? What does this prove? How does this prove it?
Proof by H. Perigal (1830) and H. E. Dudeney (1917) See Cut the Knot:
Olimpiada București 1.
Construction of a Parallelogram
Unit Circle Investigation 2
Happy New Year! Team 2 -10
Point Park Points of Concurrency
Triangle Lines of Concurrency