This is an engineering statics question, I on trig

[GreenAce92]

1. If cylinder E weighs 30lb and theta = 15 degrees, determine the weight of cylinder F
2. Sigma F = 0 (Statics question)
3. I have gotten my separate components but I don't know how to solve the equations this sounds really stupid since I'm in calc III and physics II but my brain is just crapping out on me.

I have attached a sketch of the problem
The only thing(s) that are given are the three angles, and one weight.

I am having a hard time figuring out how to solve these equations.

So far I have
Sum(x) = 0 = -Fab cos30 + Fbc cos15
Sum(y) = 0 = Fbc sin30 - 30 - Fab sin15

I even have the solutions on hibbeler however I want to learn how to solve these equations, its definitely a basic concept that I should know how to do, that is solving trig problems.

 

[GunnaSix]

Can you solve the first equation for F_{ab} in terms of F_{bc}? Once you do that, you should be able to plug that into the second equation and solve for F_{bc}.

 

[GreenAce92]

Even with opposite signs /components?
I will try
Thank you

Question:
For the FBD on knot B
Can I not use the properties of angles that are symmetrical about a line segment to assume that Fcb cos 15 = 30cos15?

Actually in the physical sense that's not correct seeing as there is another tension force on the other side of knot b.

 

[GreenAce92]

I think I've got it, I just hit a dumb wall of "I can't do trig even though I'm in calc III"