Dodecagon Construction and Tesselation

 

Step 7: Next, we'll find the midpoint between a pair of adjacent hexagon points, along the arc of the outer circle. Start by drawing a partial circle of radius approximately 0.75R on any point.
Step 8: Draw another partial circle of radius approximately 0.75R on the neighboring point. (This circle must be the same radius as the one in step 7, but the exact value is not important.) The two partial circles intersect at two points.
Step 9: Draw a line through the two points where the two partial circles intersect, and mark the point where the line intersects the outer circle.
Step 10: Draw a circle of radius R around the new point, and mark the two places where the circle intersects with the first circle. Deja vu?
Step 11: Continue drawing circles of radius R centered on new points, and mark the intersections with the first circle.
Step 12: Six new points are marked on the original circle.

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Images © 1999 Aaron Ferrucci except where otherwise noted.