# Basic Statics

by 00PS
Tags: basic, statics
 P: 12 For problem 2, r is just the distance from O to a point in the line of action of force F. In other words, this is just the distance from O to B. I believe this is <4, -3, 1.5>. I'm not sure as to how you would use a dot product to find theta x, y, and z. However, the easiest solution here is to break your force F down into components (ijk form). You can do this by taking F times the unit vector of the force. The unit vector is just the direction components of the force divided by the magnitude of the direction components. In other words: F[(4/$$\sqrt{106}$$)i - (3/$$\sqrt{106}$$ )j - (9/$$\sqrt{106}$$ )k] This will give you distinct Fx, Fy, and Fz components for the force F and you can find thetax, thetay, and thetaz forms by: thetax = cos-1(Fx/F) thetay = cos-1(Fy/F) thetaz = cos-1(Fz/F) I hope this helps. :)