Hope, one of my readers, asked me how to draw a line tangent to two circles. This is a great question because it isn’t very obvious at first. Here’s how you do it.
Start the LINE command and type TAN to start the tangent object snap. Click on the first circle near where you expect the line to be tangent to.
Then type TAN again and click on the second circle.
AutoCAD will draw a line between the two circles perfectly tangent to both of them.
Great question Hope!