How do you calculate tension forces using trigonometry?

[physicx_1]

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

 

[Quinzio]

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...

 

[physicx_1]

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?