construction a perfect Enneadecagon -2

If you have construct a 6 times angel(see last blog for the details.), it is pretty easy to use compass only to construct a perfect Enneadecagon. The right picture show the detail steps.

You can use the A19A1 angel to construct Enneadecagon also but the max error will be 3.8E-4, a slight big. But for sure , the compass will not find the error.

The nonconstructive regular polygon can be always constructed by a some complex method. But for realistic , I setup some rules for it:

1. In a 10x10 square, , the min units is 1/4.
2.the steps is not over 20 or the numbers of polygon.
3.The error is less than 0.05° for accumulation error.

My target is to finish 25 before next Chinese New year。