1, randomly point out point A and point B on the paper and connect AB;

2. Draw an arc with B as the center and a length greater than AB/2 as the radius;

3. Draw an arc with a center and the same radius in step 2;

4. The intersection of two-point arcs at points C and D;

5. connect point c and point d;

6. The line made is vertical.

Extended data:

7. Ruler drawing refers to drawing with scale-free ruler and compass. Ruler drawing is a mathematical discipline that originated from ancient Greece. Only compasses and rulers are used, and only a limited number of times are allowed to solve different plane geometric drawing problems.

8. Requirements:

(1) The ruler must be scaleless and infinitely long, and only the fixed edge of the ruler can be used. You can only use it to connect two points together, and you can't draw scales on them;

(2) Compass can be opened to infinite width, but there can be no scale on it. It can only be pulled out to the length of the previous structure.