Truss Homework: Solving for Joint Forces using Method of Joints

[bnosam]

Homework Statement

http://oi59.tinypic.com/2h65cm1.jpg[/B]

Homework Equations

The Attempt at a Solution

[/B]
All triangles: angles A = B = 53.13 degrees, angle C = 73.74 degrees

from cosine law and the 180 degree ruleBut it looks like all of the joints in the bridge have more than 2 forces? Which joint should I start at?

I was going to start at B but it looks like i have the 3000 lb force, then BC, BE and BA forces which would be too many.

 

[PhanthomJay]

Homework Statement

http://oi59.tinypic.com/2h65cm1.jpg[/B]

Homework Equations

The Attempt at a Solution

[/B]
All triangles: angles A = B = 53.13 degrees, angle C = 73.74 degrees

from cosine law and the 180 degree ruleBut it looks like all of the joints in the bridge have more than 2 forces? Which joint should I start at?

I was going to start at B but it looks like i have the 3000 lb force, then BC, BE and BA forces which would be too many.

Always determine the support reactions first. Then start at a joint or joints where there are just 2 unknown member forces, then proceed to the others.