Edit: Nevermind, it has been resolved. 1. The problem statement, all variables and given/known data I have been attempting to solve what seems like a relatively pedestrian statics questions, but for some reason my answer is being marked as incorrect. The problem is as follows: Determine the magnitude and coordinate direction angles of the resultant force acting at A. Given that F_B = 640N and F_C = 450N. http://imgur.com/U3dSG 2. Relevant equations N/A (no specific equations needed) 3. The attempt at a solution I solved for the value of the resultant vector without any trouble by assigning point A as the origin and adding the components of the two original vectors. This gave me a value of 998.05=R. The resultant vector had the equation of 626.667i+13.33j+776.667k. My attempt at solving for the coordinate angles ended in failure: For example: alpha=cos^-1(626.667/998.05)=51.1 degrees, which is incorrect. Any thoughts would be greatly appreciated.