How do you calculate tension forces using trigonometry?

AI Thread Summary
To calculate tension forces A, B, and C in a system with a suspended mass of 120 kg at angles of 60 and 25 degrees, trigonometric principles are applied. The total weight of the mass is calculated as 1177.2 N. The relationship between the tensions is established as A + B = C, with A and B being components of C. The user attempts to derive the tensions using sine functions but expresses uncertainty about the calculations. Final values provided for tensions are A = 1359.31 N and B = 2785.49 N, which require verification for accuracy.
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Homework Statement


angle 1 is 60
angle 2 is 25
and the suspended mass is 120kg

CALCULATE THE TENSIONS FORCES A, B, AND C
[PLAIN]http://img52.imageshack.us/img52/1412/unledfm.jpg

Homework Equations


The Attempt at a Solution


I understand you have to use some triangles and some trigonometry. But I am not sure how.

here is my attempt

120 X 9.81 = 1177.2 = c?

so a + b = C?

and a = half of c and b = half of c?

and then a = sin60 = half of c divided by a ?

I have no idea. please help
 
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Start thinking of the conjunction point of ABC.
In which directions it could basically move ?
If it doesn't move, it's because there's a balance...
 
yea, there is a balance. but I never said it would move or anything like that.

I've gotten answers of a = 1359.31
b=2785.49

can anyone check of that's right?
 
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