1, a stick: stick a known straight line with a right angle of a triangle. A known straight line can be regarded as a right-angled side of a triangle. Some students can't stick a straight line. You can overlap the straight line with a ruler first, and then stick a triangle on the ruler.

2. The second measure: move the triangle to find points outside the straight line. Note that in the process of moving, the lower straight line should be attached to the triangle.

3. Triple connection: connect with a pen.

4. Four marks: the last mark is the right-angle symbol.

Expand knowledge:

Intercept two points on a straight line with arbitrary length as radius, and then take these two points as the center and the length greater than the origin as the radius. The line between the intersection of two arcs and the origin is a vertical line.

Verticality is a special case of intersection. When they intersect at an angle of 90 degrees on the same plane, the two straight lines are perpendicular to each other. One of them is called the perpendicular of the other line, and their intersection is called the vertical foot.

Ruler drawing is a mathematical discipline that originated from ancient Greece. Refers to drawing with scaleless ruler and compasses. The ruler must have no scale and can only be used to make straight lines, line segments, rays or extended line segments; Compass can be opened to infinite width, but there can be no scale on it. They can only be used to make circles and arcs.

Therefore, ruler drawing is different from general drawing. All drawing tools can be used, including trigonometric ruler and protractor, which can be measured during operation, but ruler drawing cannot be measured during operation.