Henry Ernest Dudeney/Modern Puzzles/139 - A Crease Problem

Modern Puzzles by Henry Ernest Dudeney: $139$

A Crease Problem

Fold a page, so that the bottom outside corner touches the inside edge and the crease is the shortest possible.

That is about as simple a question as we could put,

but it will puzzle a good many readers to discover just where to make the fold.

I give two examples of folding.

It will be seen that the crease $AB$ is considerably longer than $CD$, but the latter is not the shortest possible.

Sources

• 1926: Henry Ernest Dudeney: Modern Puzzles ... (previous) ... (next): Geometrical Problems: Various Geometrical Puzzles: $139$. -- A Crease Problem
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Geometrical Problems: Paper Folding Puzzles: $366$. A Crease Problem