# Three-Force Member

1. Oct 30, 2008

### Melawrghk

1. The problem statement, all variables and given/known data

2. Relevant equations
None

3. The attempt at a solution
The prof told us to treat the three-force member as an equilibrium of particle question. So here is the FBD and the triangle I set up for the particle equilibrium:

I don't know where to go from there.. I mean I know it's a right angle triangle, where I know the hypotenuse, but that's really it. Help? :)

2. Oct 31, 2008

### PhanthomJay

Your first FBD is good. It is usually best to break up the known (3kN) and unknown (A and B) forces into their x and y components. Then just use the 3 equilibrium equations (sum of x forces =0, sum of y forces = 0, and sum of moments about any point = 0) which will give you the required 3 equatiions to solve for the 3 unknowns A, B, and alpha.

3. Oct 31, 2008

### Melawrghk

Thanks Jay. I know how to do it with the equilibrium equations actually. But I'm having problems doing it using the three-force member theory...

4. Oct 31, 2008

### PhanthomJay

Last edited: Oct 31, 2008