(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Find the reaction in the socket and joint at O and the tension in each cable.

http://img108.imageshack.us/img108/7585/hwstaticod1.jpg [Broken]

2. Relevant equations

[tex]\sum{F_{x}}[/tex] = 0

[tex]\sum{F_{y}}[/tex] = 0

[tex]\sum{M}[/tex] = 0

r x F = M

3. The attempt at a solution

My teacher actually solved the problem for us. But I when I go back and tried to follow what he did, I came across a few problem. So I'll just start with question 1 first, hopefully I'll be able to solve the rest.

First, my teacher list out all the unit vector.

Tac= [tex]\frac{-1}{\sqrt{6}}[/tex]i + [tex]\frac{1}{\sqrt{6}}[/tex]j - [tex]\frac{2}{\sqrt{6}}[/tex]k

My question is, how can I look at the graph and get i, j, k? I understand where the [tex]\sqrt{6}[/tex] comes from, but not the number on top.

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# Homework Help: Static: Equilibrium 3D

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