# The Naked Scientists Forum

### Author Topic: Three Points  (Read 2341 times)

#### pink_person

• Jr. Member
• Posts: 29
##### Three Points
« on: 17/04/2005 00:05:33 »
Okay, i have tried to figure this out, and i know that triangles help
a bridge better support a heavy weight, but what is it exactly that
makes it work? i can't seem to put it into words...or an equation...

Pink

#### daveshorts

• Moderator
• Neilep Level Member
• Posts: 2583
• Physics, Experiments
##### Re: Three Points
« Reply #1 on: 17/04/2005 02:53:09 »
I am not sure if this is just restating the obvious but hey...

If you have a triangle, you cannot move one of the corners relative to the other two without changing the length of a side, so it has to be rigid.

Looking at other shapes, in order to move one point the only way I can do it is by moving at least 3 others, in a triangle there are only two other points so you can't..

You could possibly proove this using cunning geometry but it is far too late, and I need to go to bed.

#### The Naked Scientists Forum

##### Re: Three Points
« Reply #1 on: 17/04/2005 02:53:09 »