The haberdasher's problem is Dudeney's best-known geometrical
discovery. The problem is to cut an equilateral triangle into four
pieces that can be reassembled to form a square. A remarkable feature
of this puzzle is that the pieces can be hinged at three vertices,
to
form a chain that can be closed clockwise to make the triangle and
counter-clockwise to make the square. Dudeney rendered the figure
into a brass-hinged mahogany model, which he used for demonstrating
the problem before the Royal Society in 1905.
Solution (not for the tenacious)
Back