Android app.

Ah. SO it has extras.

This is fun, more distraction from actual work, so thanks for pointing it out. I'm stuck on 2.8 though, I can't get the 3E solution. One element has to be the tangent itself, so that doesn't leave enough elements for the way I was taught to do it (back when we inscribed all this on clay tablets, of course).

If anyone has any hints - without giving the actual answer, I'd appreciate a pointer.

You need two circles through the existing circle to get another point for the line which comes about from the intersection of the two circles. The first circle has to be placed correctly. The second circle's placement is dependent on the first.

Got it! Thanks.

I have to admit, I've stopped caring about stars for ages. I'm happy if I manage to solve the question. Currently stuck at 8.6

That's were I am, too - finding the point from which each side subtends an angle of 120° or 60°...