title: Finding angle between two unit vectors in three dimensions
body: <p>I am trying to do some basic 3D simulation but it has been 20 years since I learned this stuff in high school...</p>
  
  <p>If I have two vectors in three dimensions, how do I find the angle between them. For example I have one vector of (3,2,1) and another of (4,-5,6) how would I find the angle (in degrees or radians) between them. If I recall there was some formula to do this.</p>
  
  <p>Thanks.</p>