Intro Level Question -- Truss Analysis

[DiamondV]

Homework Statement

http://puu.sh/lKP9T/b6aea483b5.png
http://puu.sh/lKPdk/a99777477e.png
http://puu.sh/lKPkj/a9f199e959.jpg

My question is the last picture/slide which says F_DB = F_DA how? why is that?

Homework Equations

F_DB = F_DA ?

The Attempt at a Solution

 

[SteamKing]

Since the reaction C_x = 0, what does this tell you about the horizontal force in member AB?

 

[DiamondV]

Since the reaction C_x = 0, what does this tell you about the horizontal force in member AB?

Its going to be completely dependent on the 2000lb and 1000lb forces at A and B.

 

[SteamKing]

Its going to be completely dependent on the 2000lb and 1000lb forces at A and B.

Those are vertical loads. How can they influence what happens in the horizontal direction?

 

[DiamondV]

Those are vertical loads. How can they influence what happens in the horizontal direction?

I was thinking of it, that they won't have any components in x. Ah. So the entire 2000lb load is distributed along AD. And the entire 1000lb load is distributed along BD and BE.