Listing a 2D distance when all you have is 3D geometry can be tricky. I have an answer that works. I found a few bugs along the way.

Images inserted in AutoCAD have a border known as a frame. Turning this frame on and off seems fairly black and white yet there are commands and settings to control image frames so they can be on or off, front or back, plotted or not plotted in a variety of combinations. Little did we know ON/OFF was so complicated.

Below are the command prompts to draw a polyline with a line, arc, and line where the last line segment is tangent to the curve.  The part highlighted in Red shows where you enter L to get back to a line mode from arc mode during command execution.  Enter L again to choose the Length […]