Icosikaitrigon construction at 1.2E-11

It is the best solution for Icosikaitrigon construction.It take tow days to simplify the methid which can be finished in normal compass and straight method.

Enneadecagon construction at 1.6E-11

this is the solution for compass and straight to construct a Enneadecagon with least error at 1.6E-11.

tridecagon construction at error 7.6E-11

It is not a good method but the error is the best one so far. I post here for memory.