1. Applied Geometry Lesson 1-3 Postulates Objective: Learn to identify and use basic postulates about points, lines, and planes.

2. Postulate Postulate – statements in geometry that are accepted as true.

3. Postulate 1-1 Two points determine a unique line How many lines could I draw through the 2 points?

4. Postulate 1-2 If two distinct lines intersect, then their intersection is a point.

5. Postulate 1-3 Three noncollinear points determine a unique plane There is only one plane that contains points A, B, and C

6. Example Points D, E, and F are noncollinear Name all of the different lines that can be drawn through these points. Name the intersection of point E

7. Your turn Points Q, R, S, and T are noncollinear. Name all of the different lines that can be drawn through these points. Name the intersection of

8. Example Name all of the planes that are represented in the figure. plane ACG, plane AGH, plane ACH, plane CGH

9. Example Name all of the planes that are represented in the figure Plane ACF, plane BEF, plane ABE, plane ABC, plane DEF

10. Postulate 1-4 If two distinct planes intersect, then their intersection is a line.

11. Example The figure shows the intersection of six planes. Name the intersection of plane CDG and plane BCD. Name two planes that intersect in Plane BCD and plane ABH *hint: use any of the 4 points to name the plane, must name around the plane

12. Example Name the intersection of plane ABC and plane DEF.