The construction of compass and ruler refers to drawing with scale-free ruler and compass. Ruler drawing is a mathematical discipline originated from ancient Greece, so what is the method of drawing lines in ruler drawing?

1, randomly point out point A and point B on the paper, and connect AB as the line segment to make the middle vertical line.

2. Draw an arc with B as the center and the length greater than AB/2 as the radius, as shown in the figure.

3. Draw an arc with the same radius with a as the center in step ②, as shown in the figure.

4. the intersection points c and d of two-point arcs at this point.

5. Connecting CD and AB intersect at E, then CD is the center line of AB, AE=BE.

This is the end of the introduction of straightedge drawing.