How Is the Right Triangle Used in Truss Force Calculations?

[mohamadali]

Hi, I have a, I believe simple, problem. I am studying for a Statics final and while doing problems with a Truss I came to a problem that I did not know how to solve. It is already solved for me, but I do not get how. The truss has a force coming out from the side but instead of an angle there is a right triangle. I do not understand how to use the triangle. I will upload a picture of the problem and the answer. If anyone can help me understand how the triangle is being used to compute the problem I would greatly appreciate it! Thanks in advance!

For example I do not understand where or why they get (4/5)Tcd or 130(12/13)

Direct Link:: http://i.imgur.com/ee9zP.jpg

 

[mohamadali]

oh nvm i think i got it, 3, 4 , 5 triangle!

 

[radou]

Shouldn't you be familiar with basic trigonometry in order to deal with statics? What are the relations in a right triangle?

 

[TaxOnFear]

I think you need to do some revision before your final. Look up the ratios of sine, cosine and tan.