2. Important Concepts

5. Postulates The geometry concepts that you are going to study through this course are largely based on ideas set forth more than 2000 years ago by the Greek mathematician Euclid. His series of books, Elements, is the first known work in which a logical deductive system of reasoning is used as a mean of unifying all mathematical knowledge. The essential doctrine of Elements is that when certain set of fundamental ideas or understandings are assumed to be true, all other mathematical results can be logically derived and proved from these foundations. To that end, the first of the thirteen books in Euclid’s Elements presents five postulates(also known as axioms). Today we are going to learn some of these postulates.

7. S = {(1,2)}

8. SUMMARY LESSON 1.1 Undefined terms: Line Point Plane Concepts Collinear Coplanar Segments and Rays Opposite rays Ray End point Segment Postulates Points, lines and planes 1-1-11-1-21-1-3 Intersection of lines and planes 1-1-4 1-1-5

11. JK is 4.5 cm