1, first draw a line segment (bc) with a ruler.
2. Adjust the fixed length of the compass to a fixed value, which is more than half of the length of the line segment seen by naked eyes.
3. Draw two intersections on both sides of the line segment with compasses. For example, if the line segment AB is horizontal, first draw an arc above and below with A as the endpoint, and then draw an arc above and below with B as the endpoint, which has two focuses with the previous two arcs.
4. The line obtained by connecting two intersections with a ruler is the midline of the line segment, also called the median vertical line, and the intersection of the midline and the line segment is the midpoint (point E) of the line segment.
Step 5 connect AE
Draw a bisector of an angle with a compass. First draw a circle with any length (less than two angles) as the radius, and find the intersection of the circle and two angles. Then take any length as the radius and two intersections as the center, and get the intersection of two arcs. The vertex connecting the angle and this intersection point is the bisector of the angle.