Petr-Douglas-Neumann Theorem

A hexagon (points A to F) has been prebuilt as example. Click "Generate" button to start the below animation:[br]1. For n-sided polygon, calculate n-2 consecutive angles with common difference = 360°/n.[br]2. For each side of polygon, create an isosceles triangle with apex angle = the angle used in this iteration.[br]3. If angle = 180°, the apex of the "hypothetical" isosceles triangle is the midpoint of the side of the polygon.[br]4. Connect the newly-created apexes as the new polygon and repeat step 2-4 until all angles are consumed.[br]5. Finally a regular n-sided polygon is created.[br][br]While animating...[br]1. try to move any points to transform the initial polygon. Can another regular n-sided polygon still be created?[br]a) initial polygon becoming a concave polygon[br]b) initial polygon becoming a disconnected polygon[br]2. try to toggle "outside" flag to "flip" the direction of the above isosceles triangle creation. Can another regular n-sided polygon still be created?[br]3. try to "shuffle" to consume the angles in different order. Can a regular n-sided polygon still be created? Any special of this polygon as compared with previous one?[br][br]Is such property just conserved for hexagons only? Click "Clear" button to clear the initial polygon and use the "Polygon" tool to construct your own.[br][br]P.S. Sorry about the "oscillating" animation behavior after the final regular n-sided polygon is created. Anyway, please stay tuned.
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Information: Petr-Douglas-Neumann Theorem