1. The process of judging whether the proposition conclusion is correct by reasoning is called proof. A true proposition that is judged to be correct by logical method and used as the basis of reasoning is called a theorem.

What are the general steps to prove the proposition related to graphics?

Drawing design

known

certificate

3. What is the basis of reasoning and proof?

Known, theorem, axiom

4. What true propositions have we chosen as basic facts in junior high school mathematics?

(1) There is one and only one straight line passing through two points.

(2) Between two points, the line segment is the shortest.

(3) The vertical segment is the shortest.

(4) One and only one straight line is perpendicular to the known straight line.

(5) At a point outside the straight line, one and only one straight line is parallel to the known straight line.

In addition, it is a basic fact that a triangle has two sides and two congruences of its included angle (SAS) and a triangle has two angles and two congruences of its sandwiched side (ASA).