Make a ray that passes through the endpoint of a given line segment, and use a compass to intercept a three-length line segment from the endpoint on the ray.
The endpoint of three equidistant line segments are connecte with that other endpoint of a given line segment in a straight line,
The given line segment can be divided into three equal-length line segments by taking the bisector of three equal-length line segments as the intersection of parallel lines of a straight line and the given line segment.
2. This is more difficult.
First make the bisector of a given angle, take a point on the bisector of the angle and make a straight line perpendicular to the bisector.
Cut a line segment (AB) on this line so that it is bisected by the bisector.
Then take another point o on the bisector of the angle and make a circle with the distance from the point o as the center to the two ends of the line segment as the radius.
Then draw an arc with both ends of the line segment as the center and the length (AB) of the line segment as the radius, so that the arc intersects with two points (C and D).
Connect do and co respectively. At this point, the angle DOC is divided into three parts by ao and bo.
Then take the vertex (H) of a given angle as a circle, and cross the edge of the angle with E and F..
The parallel line as DO passing through E intersects the bisector of a given angle at T.
The parallel lines that A0 and B0 intersect T intersect H in P and Q..
Connect HP, Headquarters
At this point, the given angle h is divided into three parts by HP and HQ.
My attitude towards this problem is similar.
The closer point T is to point H, the more approximately it is divided into three parts.
That is to say, the closer the angle DOC is to the angle h, the more approximately it is divided into three parts.
Only when point T coincides with point H can it be completely trisected.
By adjusting the length of AB and the position of O point.