Circle into three parts can be divided in two ways.

For one of them you will need a compass and a ruler, and the second - ruler and protractor.

Which is preferable - you decide.

You will need

- - compasses
- - line
- - protractor

instructions

1

Given a circle of radius R. It is necessary to divide it into three equal parts using compass. Open the compass on the value of the radius of the circle. You can use with the line, and you can put the needle of a compass in the center of the circle, and a leg to take the circle describing a circle. The ruler in any case still is useful pozzhe.Ustanovite compass needle at any place on the circle, which describes a circle and pencil, draw a small arc that intersects the outer contour of the circle. Then set the compass needle found in the intersection point and once again draw an arc with the same radius (equal to the radius of the circle). Repeat these steps until the next intersection point coincides with the first. You get six points on the circumferential equally spaced. It remains to choose the three points through one line and combine them with the center of the circle, and you will get divided sodium circle.

2

To divide the circle into three parts with the help ofprotractor, it suffices to recall that a full rotation around its axis is 360 ° -. Then, an angle corresponding to one third of the circle is 360 ° - / 3 = 120 ° -. Now set aside three times the angle of 120 ° - on the outside of the circle and connect the points obtained at the center of the circle.