A postulate is a statement that is assumed to be true without proof. In all math systems,
certain things are assumed to be true. By stating these postulates openly, the reader can
clearly see what the writer assumed.
Euclid included five postulates in his work:
- A straight line can be drawn from any point to any point.
- A finite straight line can be drawn in any straight line.
- A circle can be drawn with any point as the center and any radius.
- All right angles equal one another (have the same measure).
- If a straight line crossing two straight lines makes the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which are the angles less than the two right angles.