How to divide a circle

The division of a circle into equal parts is usually used to build regular polygons. In principle, it is possible to divide a circle into pieces with a protractor, but sometimes it is inconvenient and inaccurate.

Instruction

1. To divide a circle into three equal parts, spread the compass to the radius of the circle. Then set the needle of the compass on one of the axial lines and build the auxiliary circle. Three equal parts are indicated by the points of intersection of auxiliary and main circles and a point lying at the opposite end of the centerline.
2. To divide the circumference into six parts, then do the same for the other axis. Then get six points on the circle.
3. The division of the circle into four parts - trivial task. Four points on the intersection of two perpendicular axial and circumference of a circle will divide the circumference into four equal parts. To divide a circle into 8 parts, it is necessary to divide an arc corresponding to 1/4 of the circumference in half. Then breed a pair of compasses to the distance marked in red in the figure, and delay is the distance from the already obtained four points.
4. To divide a circle into five equal parts, first divide the radius on centerline in half. At this point install the needle of the compass, and stylus take before crossing perpendicular to this axis and radius of the circle. In the figure this distance is shown in red. Delay is the distance on the circumference, starting from the axis, and then shifting the compass to the resulting intersection.
   Repeat all these actions mirror to break up a circle into 10 equal parts.