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A woman lifts a 7.2-kg barbell in each hand with her arm in a horizontal position...

A woman lifts a 7.2-kg barbell in each hand with her arm in a horizontal position at the side of her body and holds it there for 3 s. The deltoid attaches 13 cm from the shoulder joint and makes a 13∘ angle with the humerus. The barbell in her hand is 0.55 m from the shoulder joint, and the center of mass of her 4.0-kg arm is 0.24 m from the joint.

A) Determine the force that the deltoid exerts on the humerus.

B) Determine the magnitude of the force that the lifter's shoulder joint exerts on her humerus.

C) Determine the direction of the force (measured clockwise from the positive x-axis) that the lifter's shoulder joint exerts on her humerus.

I need help especially on B and C -- been stuck on B for like half an hour! Please help

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