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Engineering Static Equilibrium

  • Thread starter Mason98
  • Start date
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Homework Statement
Sin for Y axis and Cos for X axis?
Homework Equations
Sin = opp/hyp Cos = Adj / hyp
When calculating static equilibrium, i know that you have to split for example, F1 into F1x and F1y. when using soh/cah/toa is it always SIN for the Y axis and always Cos for the X axis? i've been following this method and getting it wrong some times it's really stressing me out, Thanks for any help in advance.
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Last edited:

Doc Al

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when using soh/cah/toa is it always SIN for the Y axis and always Cos for the X axis?
No. It all depends on what angle you are using. If the angle is with respect to the x-axis, then fine: The x-component would use cosine, etc. But if the given angle is with respect to the y-axis, things are reversed.

Remember that sinθ = cos (90° - θ).
 
3
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so that is how in the picture Fax is sin because the angle given is in respect to the y axis which would mean to use sin?
 

Doc Al

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so that is how in the picture Fax is sin because the angle given is in respect to the y axis which would mean to use sin?
Exactly!
 
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NascentOxygen

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But if you adopt this as a new rule-of-thumb, you'll still be in a pickle when the problem gives you an angle which is relative to neither the x nor y axis.
 

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