Static Equilibrium

[Bones]

1. The problem statement, all variables and given/known data
Three forces are applied to a tree sapling, as shown in the figure, to stabilize it. If vector F A = 380 N and vector F B = 260 N, find vector F C in magnitude and direction.
http://www.webassign.net/gianpse4/12-45.gif


2. Relevant equations



3. The attempt at a solution
X direction:
380N+260N*cos105+FC*cos(theta)=0
FC*cos(theta)=-312.7N

Y direction:
0N+260N*sin105+FC*sin(theta)=0
FC*sin(theta)=-251.1N

Magnitude: sqrt(312.7^2+251.1^2)=401N

Can someone please check this for me? I am not sure whether or not it is correct.

Thanks!

[HallsofIvy]

Yes, that calculation is correct. However, you haven't yet found the angle. Of course, you can get that by dividing FC sin(theta) by FC cos(theta).