Drawing method of regular pentagon] (1) The approximate drawing method of regular pentagon with known side length is as follows: ① Draw an arc with line segment AB equal to fixed length L, centered on A and B respectively, with known length L as the radius, draw an arc with the perpendicular of AB at K ③ Draw an arc with center C and radius of known side length AB, and draw A, B, M and N respectively. Each point is approximately the required regular pentagon. (2) Drawing method of inscribed regular pentagons in a circle: ① Draw a circle with O as the center and R as the radius, and make mutually perpendicular diameters MN and AP. ② Divide by the radius to get OK=KN. ③ Draw an arc with K as the center and KA as the radius, and intersect with OM at H, where AH is the side length of a regular pentagon. ④ Draw an arc with the radius of OM in the middle of the circle with the chord length of Ah. Connect these points in turn to get the regular pentagon g.3. Folk formulas draw regular pentagons. Introduction: "The ninth five-year plan, the fifth nine-year plan and the eighth five-year plan are divided." Method of drawing lots: 1. Draw the middle vertical line of AB line, and the vertical foot is g.3. Cut GH and HD continuously on L to make GH = 5.9. HD = 5.9/5 * 10mm = 1 1.8mm 4。 After h, do EC⊥CG. On EC, the intercept HC = He = 8/5 *10mm =16mm. Adding DE, the pentagon ABCDE is an approximate regular pentagon with a side length of 20 mm Here are two methods for reference only: 1. The approximate drawing method of a regular Pentagon with known side length is as follows: (1) Draw an arc with a fixed length L with A and B as the center and the known length L as the radius, and intersect with the midline of AB. (2) centered on K. Draw an arc with CH=2/3AB (3) as the center and known side length AB as the radius, and connect points A, B, N, C and M in turn to make the required regular pentagonal AP. (2) The drawing method of a circle inscribed with a regular Pentagon is as follows: (1) O. OK=KN. (3) Draw an arc with K as the center and KA as the radius, and intersect with OM at H, where AH is the side length of a regular pentagon. (4) Take AH as the chord length, cut points A, B, C, D and E on the circumference, and connect these points in turn to obtain a regular Pentagon. Connection point! !