Member forces of a simple Truss

[twenty5]

Homework Statement

hi all, I've got a simple truss question. Which asks to solve for the member forces. I've learned the stuff in class, but from what I see here, I don't know which joint to start with. With the provided image below, can someone please direct me to which joint I should start with? and I'll try to take that concept into the other questions. Thanks!

More info. I'm trying to solve through method of joints... so I'm breaking it up into many joints

Homework Equations

(net)F_x = 0
(net)F_y = 0

[PLAIN]http://img571.imageshack.us/img571/2452/truss.png

The Attempt at a Solution

I started by assuming some forces on the supports

+Ay, +Dx, and +Dy

I wrote out all of the joints with their equilibrium equations, but they all have too many unknown variables :/. If someone can just give me a push start it would be nice ^^; thanks!If I start with Join A, I get:

F_x = 0 ; a + dcos36.9 =0
F_y = 0 ; A_y + dsin36.9 = 0

pretty much happens with the rest of the joints too :S... Unless there are some substitutions to be done ^^

 

[twenty5]

OOOH NVM NVM NVM NVM.; I GOT IT. thanks for the consideration of this thread though. ^^

For those who may also encounter this ^^ you have to use the moment equations to get the reactions at the supports. From this, you can calculate the rest of the values ^^ very happy. thanks ( thanking myself hahaha )

 

[PhanthomJay]

Yes, always solve for the reactions first, then start with the simplest joints. Joint B is very simple, then joint A and D. The rest will follow.