[Trusses] Problem finding forces in members

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Homework Help Overview

The discussion revolves around finding forces in members of a truss structure, specifically focusing on the components of forces and their geometric relationships. Participants are examining the derivation of certain trigonometric factors related to the angles and lengths in the truss system.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the origins of specific trigonometric ratios (5/sqrt29 and 3/sqrt34) in relation to the geometry of the truss. There are mentions of using moments about points A and B, and the challenges posed by multiple unknowns in the system. Some are considering the use of systems of equations to find forces in members HG and HC.

Discussion Status

The discussion is ongoing, with participants expressing confusion about the application of trigonometric relationships and the method of moments. Some guidance has been offered regarding the geometric interpretation of the ratios, but there is no explicit consensus on the approach to take.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is an acknowledgment of fatigue and frustration among some participants, indicating the complexity of the problem at hand.

student314
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Can anyone please explain where does 5/sqrt29 and 3/sqrt34 come from? I already got BC/know how to find BC, but in my own method, I tried to use moment about A or B, knowing that there is HGx, HGy & HCy, HCx -- there are way too many unknowns @ H.

So, looking at this, I'm wondering where does 5/sqrt29 and 3/sqrt34 come from? Please see the image for reference:

http://i.imgur.com/4ruELnE.png

Thank you
 
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Apparently I'm told to use the system of equations to find HG? Or HC? What does this mean, and how?
 
student314 said:
Can anyone please explain where does 5/sqrt29 and 3/sqrt34 come from? I already got BC/know how to find BC, but in my own method, I tried to use moment about A or B, knowing that there is HGx, HGy & HCy, HCx -- there are way too many unknowns @ H.

So, looking at this, I'm wondering where does 5/sqrt29 and 3/sqrt34 come from? Please see the image for reference:

http://i.imgur.com/4ruELnE.png

Thank you

When you see factors like 5/Sqrt(29) or 3/Sqrt(34) in truss problems, these almost invariably arise from the geometry (or more accurately, the trigonometry) of a truss member.

In the equation for ΣMC , what is the length of member HG? What is the horizontal component of the force in member HG?
 
HGx = HG(5/sqrt(29))? Then times 5 distance to moment C?

God, I'm so tired, I've been working and trying hard to figure out all day, I'm going to sleep for now
 
student314 said:
HGx = HG(5/sqrt(29))? Then times 5 distance to moment C?

God, I'm so tired, I've been working and trying hard to figure out all day, I'm going to sleep for now
Yep.
 

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