Equilibrium when applied to muscles and joints Help, please

[confusedbyphysics]

This seems like it should be easy but I am not sure what to do. Heres the problem:
The picture to the problem is here: http://www.webassign.net/giancoli/9-65alt.gif
"(a) Calculate the magnitude of the force FM required of the "deltoid" muscle to hold up the outstretched arm shown in Fig. 9-65. The total mass of the arm is 2.8 kg and = 12°.
(b) Calculate the magnitude of the force FJ exerted by the shoulder joint on the upper arm.
I found a) by doing .12 m (sin 12) F - .25 m (2.8 kg) (9.8 m/s^2) = 0. F = 264 N.
But how do I find the force FJ? Confused (we haven't had the lesson on this yet, but trying to get my homework done early because I have a busy week). THANKS for any help!

 

[lightgrav]

your torque looks okay.

Now that you know all the Forces, you could treat it like a chapter 3 problem
(Sum of the force components (x,y) = 0 . you DID enjoy that, right?)

OR, you can sum torques around the tendon attachment point, to = 0
(pretending that it might rotate around this attachment point)
This gives the vertical component of the joint Force (Fjx applies no torque).

 

[confusedbyphysics]

thanks lightgrav, adding up the components worked. answer turned out to be 260 N. Thank you for the help!