Triangle Animals

How many different ways can you find to join three equilateral triangles together? Can you convince us that you have found them all?
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Problem



I can join two equilateral triangles together along their edges like this:

 

Image
Triangle Animals

 

How many different ways are there to join three equilateral triangles together? (You must match an edge to an edge.)

How do you know you have got them all? You may find it useful to print out and cut up triangles from this sheet.

 

How many different ways are there to join four equilateral triangles together?

Have you got a system for checking that you have them all?



For a further challenge, you might like to look at Tri-Five.