You are given a limitless supply of triangular jigsaw pieces of type T1, T2, T3, T4 and T5

Using these pieces, you need to try to make larger triangular shapes without any overlap.

Three triangle shapes are shown in the picture below. Is it possible to create two-coloured triangles of these shapes without moving the pieces already placed?

Suppose next that you can move the pieces and choose two triangle types to work with. Which pairs of shapes can be used to make larger equilateral triangles? Which pairs of shapes can be used to make larger 30-60-90 triangles? See the video clip for a discussion on this part of the problem

NOTES AND BACKGROUND

This problem is all about either finding solutions or proving that there is no solution for any size of triangle shape.

For small triangle shapes, it is easy to check all possible configurations of pieces to check whether a solution exists. For larger triangle shapes the number of combinations of pieces gets larger extremely rapidly, and quickly reaches the point at which a check of all of the combinations is impossible, even on a supercomputer. Even if we have checked a large number of jigsaw sizes and found no solution, this does not necessarily mean that we cannot find a solution for a larger triangle shape. To find a solution, you often need to mine the depths of your cunning and ingenuity. To show that a solution does not exists you often have to use the concept of proof by contradiction .

Proving that a solution

Ideas concerning proof are discussed in the fascinating article Proof: A Brief Historical Survey