Remove one matchstick from the ones above. Then rearrange the matchsticks to create six identical triangles.
First count the matchsticks that you have now. There are 13 of them, so when you remove 1 of them you have 12 in all. Think about the number 12. It is the same as 4 x 3 , which is 4 triangles with the 3 sides. But we need 6 triangles that are identical - which brings in the idea that the triangles share sides.
Thinking of the number 12 - the other factors are 6 and 2. What Polygon has 6 sides?
A Hexagon! So can we make 6 identical triangles from a Hexagon? Go ahead and give it a try!
Create a Hexagon and use the remaining 6 matchsticks to create the diagonals and this will give you 6 identical triangles.