title: 3D Perpendicular Point on Line From 3D point
body: <p>This question has been asked before in reference to 2D. This question extends it to 3D. How do I find the perpendicular intersected point on a line from a point in 3D space?. If my line is defined by points <code>(x1,y1,z1)</code> &amp; <code>(x2,y2,z2)</code> and I have a point <code>(x3,y3,z3)</code> in space.</p>
  
  <p>How do I find the perpendicular intersection of point (x4,y4,z4) on the line from (x3,y3,z3)?</p>