Henry Ernest Dudeney/Puzzles and Curious Problems/191 - Two Squares in One/Solution

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Puzzles and Curious Problems by Henry Ernest Dudeney: $191$

Two Squares in One
Two squares of any relative size can be cut into $5$ pieces, in the manner shown below,
that will fit together and form a larger square.
Dudeney-Puzzles-and-Curious-Problems-191.png
But this involves cutting the smaller square.
Can you show an easy method of doing it without in any way cutting the smaller square?


Solution

Dudeney-Puzzles-and-Curious-Problems-191-solution.png

Place the two squares together so that $AB$ and $CD$ are straight lines.

Locate the centre point of the larger square.

Draw $AD$

Draw $EF$ and $GH$ through that centre point parallel to and perpendicular to $AD$ respectively.

Then you can cut out pieces $1$, $2$, $3$ and $4$, which, together with the smaller square $5$, fit together to form the big square of side $AD$.


Historical Note

This dissection was discovered by Henry Perigal in about $1830$, and published by him in $1873$.

Martin Gardner reports on it in detail in his $1966$ collection Martin Gardner's New Mathematical Diversions from Scientific American


Sources