Division of a circle into equal parts is usually used for creation of regular polygons. In principle, it is possible to divide a circle into parts by means of a protractor, but it is sometimes inconvenient and inexact.
1. To divide a circle into three equal parts, part compasses on circle radius. Then establish a compasses needle on one of center lines and construct an auxiliary circle. Three equal parts will be designated by points of intersection of auxiliary and main circles and the point lying on the opposite end of the center line.
2. To divide a circle into six parts, do the same for another axial. Then six points on a circle will turn out.
3. Division of a circle into four parts - a trivial task. Four points on crossing two perpendicular axial and circles will divide this circle into four equal parts. To divide a circle into 8 parts, it is necessary to halve the arch corresponding 1/4 circles. Then to part compasses on the distance designated red in the drawing and to lay off this distance from already received four points.
4. To divide a circle into five equal parts, for a start halve radius on the center line. In this point establish a compasses needle, and take away a slate pencil before crossing perpendicular to this radius axial and circles. In the drawing this distance is shown red. Lay off this distance for circles, starting with axial, and then transferring compasses to the turned-out point of intersection. Repeat all these actions specularly to break a circle into 10 identical parts.