Required accessories - pencil, compass, unmarked straightedge
Odd proportion angles (there is a proportion of the steam angles) of the element 3 (which may be 5,7,9, ...) and the base angle [TEX] 45 ^ o[/TEX] (which can be any angle which is obtainable by means of compass and straightedge)
The angle CAB [TEX]45 ^ o[/TEX] can be obtained with a compass and unmarked ruler, he added angles (each have [TEX]45 ^ o[/TEX]) DAC and EAD, obtained angle EAB [TEX]135 ^ o[/TEX]is the starting angle
Merge points E (D, C, B) and get a longer ED (DC, CB)
Along the DC from the point C draw is normal that intersects the segment AB, the intersection is a point G
Divider AG and from point G draw a circular arc to a longer EA and H get the point, and the arc GH, join the dots G and H and get along GH
Longer GH (ED, DC, CB) are equal, the arc EB's first circular arc can be made smaller or larger with a constant radius AB, arc GH is the second circular arc can be made smaller or larger with a constant radius AG
INCREASING THE ANGLE
the starting angle EAB add angle FAE [TEX]15 ^ o[/TEX] get the angle FAB [TEX]150 ^ o[/TEX] - continued in the next post