(1) makes a line segment equal to a known line segment;

(2) Make an angle equal to the known angle;

(3) bisecting the known angle (i.e. the bisector of the known angle);

(4) perpendicular bisector is a line segment;

(5) Make a point perpendicular to the known straight line.

2) There are many graphic transformations in junior high school, so the drawing principle is different.

Take five basic drawing methods, which can be proved by the knowledge of triangle congruence. Let me give you an example, such as the bisector of a known angle.

It is called ∠ABC.

Find the bisector of ∠ABC.

Practice: (1) Draw an arc with point B as the center and any length as the radius, and intersect AB and BC at points D and E respectively; (2) Draw an arc with d and e as the center and the length greater than 1/2DE as the radius, and the two arcs intersect at point F; (3) Lei BF. The ray BF is the bisector of ∠ABC.

(Principle) Proof: According to the drawings, BD=BE, DF=EF, BF=BF.

Then ⊿ BDF ≌ δ BEF (SSS), so ∠ABF=∠CBF.

There are many contents in the graphic transformation part of junior high school, and there are not one aspect involved, so the drawing principle is not one. For example, making a triangle according to its two sides and included angle is a judgment method based on triangle congruence (SAS); Another example is the translation of graphics, the principle is the nature of translation (the corresponding line segments in the translated graphics are parallel and equal, and the line segments between corresponding points are parallel and equal); There are many contents, and the specific principle depends on the specific topic.