# Moment of force and static equilibrium

1) Problem:
An individual holds a ball of mass 3 kg in his hand in static equilibrium. The biceps brachii attaches a distance of 2 cm from the centre of rotation of the elbow joint, and the muscle's line of action is directed at an angle of 115° counter clockwise from the forearm. The forearm has a mass of 1.5 kg. The forearm's centre of mass is located a distance of 18 cm from the elbow joint. The distance from the elbow joint to the point at which the ball is held in the individual's hand is 45 cm. Assuming that the biceps brachii is the only muscle contributing to elbow flexor moment, what is the magnitude of the tension running through the biceps brachii?

http://imgur.com/1GQ3nNv

2) Relevant equations:

f=ma, Static Equilibrium: Em = 0

3) My solution
I know that i have to convert the mass of the forearm and the weight to Newtons, but what do I do with the angle. Fb = force biceps:

-29.43(0.45) - 14.715(0.18) + Fb(0.02) = 0
fb = 794.61

However, I can't figure out when to incorporate the angle (115) at which the biceps is flexed :/