Triangle is the Only Rigid Polygon!

Today we have learned about triangles in Grade 8s and 9s. One of the interesting parts of the lessons was about triangles' rigidity.

Triangles cannot be bent or be forced out of shape; they are not flexible. Therefore triangular shapes are used in modern constructions for safety reasons.

Here are some examples:

(This second bridge is Thanlyn Bridge)

Then we made an experiment. When in a triangular shape things become stronger and in the following photos we can see how an A4 paper becomes much more stable. Only thing you need to do is to fold it like a fan.