Hi flatdog - you can solve it geometrically like this-

Start by drawing an 11 sided polygon of any size, and then draw a circle from one vertex to a midpoint, so you will have this:



This has the layout that you want, just the whole thing is not at the specific scale that you want. So you can fix that by scaling it to your target size.

To do that, draw a second circle of the specific size that you want at the same center point as the first circle like this:



Now select the 11-sided polygon and run the Transform > Scale command.

For the scale origin pick the center of the 2 circles.

For the first reference point, pick a point on the large circle.

For the second reference point, pick a point on the small, end-sized circle.

The 11-sided polygon will now be sized to what you want, you can do a circular array using the center point of the polygon as the array origin.

- Michael