The bobline

A regular hexagon is folded back and forth along the dotted line. What fraction of the area is yellow?

Scroll down for a solution to this problem.


The yellow fraction is 11/16.

Solution by Jonathan Crownshaw.

It is easily seen that the dotted line cuts the sides on 3/4. One can then dissect the figure in equilateral triangles of side 1/4 as shown. It is now a matter of counting 66 yellow triangles on a total of 96.


Bobline haircut for a fighting lady
Like Joan of Arc, the Virgin, the heroe
She was fighting for France
For freedom with her lance
And steel on her hair
To go anywhere
The young lady
Coming from Domremy
Giving France liberty
She left to save her country
An angel holly !


🤞 Don’t miss these puzzles!

Subscribe to the weekly geometry puzzle e-mail.

Leave a Reply

Your email address will not be published. Required fields are marked *

Optionally add an image (JPEG only)