How Do You Calculate Cos 125 Degrees in Engineering Mechanics?

[w4taup]

http://imageshack.us/f/560/engineeringmechproblem.jpg/

I have a question about this problem, i was wondering where they got the cos 125degrees as well as the a=13.4 degrees. If anyone knows how they got this answer can you please tell me how?

 

[PhanthomJay]

http://imageshack.us/f/560/engineeringmechproblem.jpg/

I have a question about this problem, i was wondering where they got the cos 125degrees as well as the a=13.4 degrees. If anyone knows how they got this answer can you please tell me how?

Looks like someone made an error. That should be cos 135 degrees (180 - 15 - 30 = 135) and the rest should follow.

 

[w4taup]

lmfao thanks a lot bro, i was wondering for sooooo long how they got that :P