Imagine you have lots of copies of the two triangles pictured below:
You may wish to print off and cut out these Yellow and Green triangles.
Can you make a regular hexagon using only yellow triangles ?
Can you make a regular hexagon using only green triangles ?
Can you make a regular hexagon from yellow triangles that is the same size as a regular hexagon made from green triangles ?
Did that tell you something about yellow and green triangles, about how they relate to each other ?
When you've got inside this problem and started to feel your way around, please do take a look at Impossible Triangles? - it's the perfect follow on. There's even a video to watch to make getting started easy.
Printable NRICH Roadshow resource.