Dissection of a Square and an Isosceles Right Triangle into a Square
This Demonstration shows Dudeney's dissection of a square into a square, with an isosceles right triangle appearing in an intermediate stage.
 D. Wells, The Penguin Book of Curious and Interesting Puzzles, Penguin Books, New York, 1993 p. 269.
"Dissection of a Square and an Isosceles Right Triangle into a Square"
Wolfram Demonstrations Project
Published: December 30 2015