blem 6 If a person with weight W bends at the waist with a straight back then the force F in pounds exerted on the lowe back muscles may be approximated by the function F 3 2 89W sin 8 The angle 8 is the angle between a person s torso and the horizontal a Use the sum and difference identities to rewrite the function F 3 in terms of cosine b Suppose the person is standing straight measure the force exerted on their back c Suppose the person weighs 200 pounds