Construction of Regular Polygon of given length AB

To construct a regular polygon with length of edge AB us shown in figure 1.

Figure 1. Construction of a regular polygon with a given length of edge.

• Draw a line of length AB.  With A as centre and radius AB, draw a semicircle.
• With the divider, divide the semicircle into the number of sides  (example of number of side 7 is shown in figure 1) of the polygon.
• Draw a line joining A with the second division-point 2.
• The perpendicular bisectors of A2 and AB meet at O. Draw a circle with centre O and radius OA.
• With length A2, mark points F, E, D & C on the circumferences starting from 2 (Inscribe circle method)
• With centre B and radius AB draw an arc cutting the line A6 produced at C.  Repeat this for other points D, E & F (Arc method)