23-gon at 8E-14

11-gon at 4E-12( a little simple)

23-gon at 7.6E-14

13-gon at 4.58E-13( a little simple)

11-gon at 8.92E-13

I had found a higher method but it was very complex. I decided to find a simple method which not over 40points. this work is step in.

25-gon at 5.87E-15

I am very happy to find the first one to reach relative error at E-15. My target is to find all those regular polygon construction method at E-15. and with not over 40 points, 30x40 area.

19-gon at 6E-12 ( a little simple)

7-gon at 5.3E-11(improved)

7-gon At 1.04E-12

11-gon at 8.4E-12,( a little simple)

this method is not so simple for complete process. But for startup ,it is simple. just for reference.

11-gon at 1E-11(simple)

I am very happy to find a way to improve the method to construct Hendecagon. the orignal formula was post before but with new method, the shape looks like a ship. Hope someone can enjoy it ,espcialy with kids.

19-gon at 3E-14