The Circle by Tan Tan Radius is one of the more interesting commands in AutoCAD and requires one to indicate the position of a center of a circle simply by hovering the mouse on the side of which the circle is to be created. I don’t know of any other command in AutoCAD that uses the hovering feature of the mouse. It is for this reason that most novices find the command so confusing.
Add to that that one needs to visualize the tangent point and then indicate them by guessing.
This video explains the use of the Circle by Tan Tan Radius command and the various scenarios in which it is used. The includes how to make a circle tangent to two others both in a convex and converse fashion.
This is one of the more interesting commands which our students learn in our courses. If you are looking for training or support using AutoCAD, please contact Micrographics so we may be of assistance to you.