Hi everyone...I am in my last semester of college and physics has returned to my life.. It has been approximately 3 yrs since physics and 6 years since calculus so I am really rusty regarding classical physics (mechanics). here is my problem Listed below are three vectors that point from the origin of a right-handed orthogonal three-dimensional reference frame to the shoulder (V1 ), elbow (V2 ) and wrist (V3 ), respectively, of the throwing arm of a baseball pitcher. Note, i and j are unit vectors in the horizontal directions (j points towards home plate and i is perpendicular to j and points towards third base), and k is a unit vector pointing in the vertical direction. V1 = (10.02 i + 11.08 j + 1.10 k ) m - Shoulder V2 = (10.19 i + 11.33 j + 1.22 k ) m - Elbow V3 = (10.27 i + 11.55 j + 1.36 k ) m - Wrist I have to find a vector that points from the elbow to the wrist, the length of the forearm from the elbow to the wrist, and also the elbow angle in degrees. I am going to write out my thought process so hopefully you can correct me if I'm wrong. I believe I have to do vector subtraction in order to find this vector. I would take the V3 (wrist) - V2(elbow). I would align the tail of V2 on the tip of V3 in the negative direction and find the resulting vector. for the i unit vector it would be 10.27 - 10.19 = .09 for the j = 11.55 - 11.33 = .22 for the k = 1.36 - 1.22 = .14 I have a vector that is .09i + .22j .14k and I would find the magnitude to find the length of the forearm which would be the square root of (.09i^2 + .22j^j + .14^2) = .276 m which sounds reasonable then for the last part solving the angle of the elbow I am stumped. any feedback/help would be amazingly appreciative. thanks everyone!