Part 2
The conjecture that you should have drawn is:
Triangles are rigid shapes whereas other shapes (like squares) are not.
How did you come to this conclusion?
When moving the two figures you made with cardboard strips and paper fasteners you should have noticed that:
- The triangle would not move no matter what you did because its vertices were fixed.
- However, the square swayed side-to-side because its vertices weren't fixed.
How can this important fact about triangles be applied to the real world?
Civil Engineers use triangles in the constrution of building bridges as shown below.
Construction workers use triangles in the construction of roof frames as shown below.
They use triangles because:
- Triangles are both stable and rigid,which are two properties of triangles you just finished learning about.
- When building a bridge, the use of triangles will make the bridge strong and in turn allow the bridge to span long distances.
Can you imagine a bridge made out of a bunch of squares?
It wouldn't work!
Next, we will use this new fact about triangles to build a bridge of our own.
Proceed to "Building Bridges" to do this.
Go to Building BridgesReturn to Main Page