13-gon at 5.37E-15(P27)

19-gon at 2.39E-15(P27)

11-gon at 8.02E-15(P29)

19-gon at 3E-14 (P37)

11-gon at 5.09E-14 (P37)

this method is complex but it is better than the way I found before. It is really difficult to reach E-15.

13-gon at 4.91E-14 (P32)

23-gon at 2.39E-15 (P32)

7-gon at 7.45E-15 (P22)

it took me a lot effort to reach this accuracy. I tried traditional way I used to be but failed. So I thought it might to have some new approch and this method is one . I just found that it is hard to use currecnt computer to find a good method at E-15 as the computer don't have enough lenth for the digits. I am happy to find this. 

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

19-gon at 1.98E-12(very simple ,improved version)

13-gon at 1.16E-11

21-gon construction at 1.35E-11

19-gon construction at 1.98E-12(very simple)

21-gon construction from 7-gon

25-gon construction at 1E-10