# How to properly find equilibrium vectors when 3 or 4 vectors are present? [closed]

I'm having trouble regarding how to find the equilibrium of vectors. We were given tables with given information and had to fill them in; I'm fairly sure my initial attempts were incorrect.

first example

Vector A: mass - .2kg, magnitude - ?, direction - 20deg, xcomp -?, ycomp - ?
Vector B: mass - .15kg, magnitude -?, direction 80deg, xcomp - ?, ycomp - ?
Vector C: mass - ?, magnitude -?, direction -?, xcomp ?, ycomp - ?


A and B are no problem, I'm just not sure if I add or subtract my components to get the components for C.

The same goes for this one:

Vector A: mass - ?, magnitude - ?, direction - 0deg, xcomp - ?, ycomp - ?
Vector B: mass - ?, magnitude - ?, direction - 90deg, xcomp - ?, ycomp - ?
Vector C: mass - .3, magnitude - ?, direction - 240deg, xcomp - ?, ycomp - ?


and the oddest one:

Vector A: mass - .1, magnitude - ?, dir - 30deg, xcomp - ?, ycomp - ?
Vector B: mass - .2, magnitude - ?, direction - 90deg, xcomp - ?, ycomp - ?
Vector C: mass - .3, magnitude - ?, direction - 225deg, xcomp - ?, ycomp - ?
Vector D: mass - ?, magnitude - ?, direction - ?, xcomp - ?, ycomp - ?


NOTE: I was using f = ma, tan(angle) = a/b, and xcomp = fcos(angle) and ycomp = fsin(angle) I just didn't know what to do about the final vectors for sure.

NOTE 2: I don't need help finding the first few vectors' information, just the last ones (e.g. Vector D). More specifically, when do I add or subtract the components of the first vectors in order to get the components for the final vector and then get the rest of the information for it?

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## closed as too localized by Qmechanic♦, Emilio Pisanty, Sklivvz♦, Manishearth♦Dec 27 '12 at 16:35

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Welcome to Physics! Please see our homework policy. We expect homework problems to have some effort put into them, and deal with conceptual issues. If you edit your question to explain (1) What you have tried, (2) the concept you have trouble with, and (3) your level of understanding, I'll be happy to reopen this. (Flag this message for ♦ attention with a custom message, or reply to me in the comments with @Manishearth to notify me) – Manishearth Dec 27 '12 at 16:35

Never mind! I just used the masses to find the forces. Then used the forces and angles to find the components, used the components to find the components to find the components of the last vector, and used the last vector's components to find the angle, magnitude, and mass.

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