Henry Ernest Dudeney/Puzzles and Curious Problems/330 - The Encircled Triangles/Solution

by : $330$

 * The Encircled Triangles
 * Draw the design of circle and triangles in as few continuous strokes as possible.
 * You may go over a line twice if you wish to do so, and begin and end wherever you like.


 * Dudeney-Puzzles-and-Curious-Problems-330.png


 * How should you proceed?

Solution
It can be done in $14$ strokes.

Refer to the below diagram.


 * Dudeney-Puzzles-and-Curious-Problems-330-solution.png

Draw the straight lines $ABCDEFAGHI$ which is $9$ strokes.

Note we have visited $A$ twice during this excursion.

Draw one stroke round the circle and back to $I$ again, which is one stroke, making $10$ so far.

Draw $IJKLJ$ which is $4$ more strokes, making $14$ in all.

Note that we have gone over the short segment $AJ$ twice, while the rest of the diagram is traversed only once.

The question is flawed, in that it does not say you must perform this task without lifting the pencil from the paper.

However, from a view of the answer, it is clear that is what is meant.