physics problem truss forces?

Determine the magnitude of the force in each member of the truss shown in the figure below. A little tricky where to begin. Obviously start with point B and I get F-Fbc cos 30 = 0

That would give you Fbc but I'm not sure if I'm supposed to use cos 30 or cos 90? Any help please? Where do I go from here?

The diagram is here >> PLEASE COPY AND PASTE IT AND REMOVE THE SPACE BETWEEN tinypic and the .COM yahoo wont let me show the link on here for some reason. thank you. http://i42.tinypic .com/28i930o.jpg

2011-10-30T18:39:34Z

the bottom most length along A to C is 12' but that doesn't seem to help much. Am I missing what you are saying?

2011-10-30T19:46:29Z

Right, I got that by using F-FbcCOS30=0 then solving for Fbc = 2309

Now Im a little confused with finding Fba..

Using FbcSIN30 - FbaSIN60 = 0 plugin Fbc.. not sure if FbaSIN60 is the right way to go. Is this the correct method?

T-Rent2011-10-30T18:37:48Z

Favorite Answer

Do you have any lengths for the sides? You could try to sum the moments about A.

EDIT:
The lengths are very important. Solve your triangle with trig functions, which is simple enough. I think you should use sin 60. Which would give you a force of Fbc=2309N in compression. Then just go from there.

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