AutoCad help. How to draw a smooth curved line between a small and large circle

AutoCad help. How to draw a smooth curved line between a small and
large circle.

Hi all,

I can't remember how to draw a curved line that joins two circles
together. Imagine a circle 100mm and another circle 50mm, the
centre distance apart will be say 300mm. Lets draw a straight line
from the top of each circle and join them together.

On the bottom, instead of having a straight line, I want to make a
curved line that will be concave. That is, the centre of the line
has been lifted upwards closer to the top line. Like the opposite
of a smiley face.

What will happen is I can make a curve to join both circles but
where they join the circles will be at the quadrants. So there will
not be a smooth blended transition onto the curved line. But rather
as soon as the curved line joins the quadrant at the bottom of the
circle, it will have a bump/step there as it becomes the curved line.

It is like it needs to be joined further along the circumference of
the circle so that it blends in nice and smooth.

I used to be able to do it, but I can not remember now.

Any ideas?

Peter
Australia