title: Drawing line perpendicular to a given line
body: <p>I have start and end coordinate of a line. I want to drawn another line sticking at the end of this this such that they will be perpendicular to each other.</p>
  
  <p>I am trying to do this using the normal geometry. Is there any high-level API there in MFC for the same.</p>
  
  <p>Thanks</p>