Ruler compass drawing method
In mathematical geometry, an angle consists of two sides and a vertex. The vertex here is that both sides have a common endpoint, and both sides can also be regarded as rays. When drawing an angle, you can draw two straight lines in different directions along a ruler, and the intersection of the two straight lines forms an angle.
Ruler drawing refers to drawing with scaleless ruler and compasses. 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. Ruler The rulers and compasses used for drawing are imaginary, which are not exactly the same as those in reality.
The ruler must have no scale, infinite length, and only one side fixed with the ruler. You can only use it to connect two points together, and you can't draw scales on them; 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. In the stage of compulsory education, students' first contact with rulers is to "make a line segment equal to a known line segment".
Therefore, the commonly used definition is based on the definition of "drawing public law", that is, each operation can only be one of the five basic operations (called five drawing public laws) that are recognized and allowed. Before each operation, the logical judgment that the operator can make to decide whether to operate and what kind of operation can only be recognized and allowed in geometry.
The definition of "public law of drawing" is: the drawing method completed by recognizing the following five preconditions and applying the following five public laws within a limited time is a legal ruler drawing method: it is allowed to select any point on a plane, a straight line or an arc. The position order of different points on the same straight line can be judged. The position order of different points on the same arc can be judged.
You can know which side of the straight line a point on the plane is on. It can be judged whether a point on the plane is inside or outside the circle. Five public laws are based on two established points and make a straight line through them. Make a circle with a certain point as the center and the distance between two certain points as the radius. Determine the intersection of two intersecting lines.