VBA or LISP: Circle Tan Tan Tan

I'm trying to create a macro to draw a circle tangent to 3 lines/arc/circles, in any combination then trim. the first problem is how do i draw the circle tan to the 3 entities (selected).

or can i use the command line: circle ttt, to feedback the selected entities picked to VBA/LISP, to be able to trim them and the circle created?

 

If that's all you're ding [e.g. its not part of something bigger], just
write a menu macro with a little diesel thrown in.

-- Mike
___________________________
Mike Tuersley
CADalyst's CAD Clinic
Rand IMAGINiT Technologies
___________________________
the trick is to realize that there is no spoon...

 

This is the same problem I faced. It is solved mathematically using Apollonius theorem.
- If you are trying to draw a circle in a triangle. You can find the centroid of the triangle and use it as a centerpoint for the circle. To find the centroid of triangle. Draw normal from midpoints of two sides of triangle. Where these lines intersect that is centroid. Find the distance between the midpoint to this point of intersection to determine radius from your circle. Use this point as center point for circle and calculated distance as a radius of circle to draw tangent circle to all sides. See if this helps.