Nine-Point Circle - Small Basic Featured Program

I wrote a program to draw a nine-point circle.  The program ID is SJV079-0.  A nine-point circle passes nine significant points defined by a triangle:

• The midpoint of each side of the triangle
• The foot of each altitude
• The midpoint of the line segment from each vertex of the triangle to the orthocenter
  

You can drag and drop each vertex of the triangle.

This program still has following issues:

• sometimes occurs divided by zero error
• orthocenter sometimes doesn't connected with lines properly

I will update this blog post (or leave comments) if these issues are fixed.  Have fun with nine-point circles!  Thanks.