五个公设如下，它们被认为是领域内自明的事实，规定了三个基本概念间的关系

The five postulates are as follows. They are considered to be self-evident facts in the field, and stipulate the relationship between the three basic concepts: <br>1. It can be made through two points and only a straight line; <br>2. The line segment can be extended indefinitely; <br>3. Any point is the center, and any length is the radius, and a circle can be made; <br>4. All right angles are equal; <br>5. A straight line and two other straight lines in the same plane intersect, if the sum of the two internal angles on the same side of the straight line is less than 180° , Then the two straight lines must intersect on this side after being infinitely extended.

The five postulates are as follows. They are considered self-evident facts in the field and define the relationship between the three basic concepts:<br>1. It can be made through two points and only one straight line can be made;<br>2. The line segment can be extended indefinitely;<br>3. A circle can be made with any point as the center and any length as the radius;<br>4. All right angles are equal;<br>5. A straight line and two other straight lines intersect in the same plane. If the sum of the two internal angles on the same side of the straight line is less than 180 °, the two straight lines must intersect on this side after infinite extension.

The five postulates are as follows. They are regarded as self-evident facts in the field, and stipulate the relationship between three basic concepts: 1. Two points can be done and only a straight line can be made; 2. Line segments can be extended indefinitely; 3. Take any point as the center and any length as the radius to make a circle; 4. All right angles are equal; 5. One straight line and the other two straight lines intersect in the same plane. If the sum of the two internal angles on the same side of the straight line is less than 180, the two straight lines must intersect on this side after infinite extension.